diff --git a/osu.Game.Tests/Chat/TestSceneChannelManager.cs b/osu.Game.Tests/Chat/TestSceneChannelManager.cs
index cdd192cfe1..3a4c55c65c 100644
--- a/osu.Game.Tests/Chat/TestSceneChannelManager.cs
+++ b/osu.Game.Tests/Chat/TestSceneChannelManager.cs
@@ -75,6 +75,8 @@ namespace osu.Game.Tests.Chat
                     return false;
                 };
             });
+
+            AddUntilStep("wait for notifications client", () => channelManager.NotificationsConnected);
         }
 
         [Test]
diff --git a/osu.Game/Online/Chat/ChannelManager.cs b/osu.Game/Online/Chat/ChannelManager.cs
index 1e3921bac0..7ab678775f 100644
--- a/osu.Game/Online/Chat/ChannelManager.cs
+++ b/osu.Game/Online/Chat/ChannelManager.cs
@@ -64,6 +64,11 @@ namespace osu.Game.Online.Chat
         /// </summary>
         public IBindableList<Channel> AvailableChannels => availableChannels;
 
+        /// <summary>
+        /// Whether the client responsible for channel notifications is connected.
+        /// </summary>
+        public bool NotificationsConnected => connector.IsConnected.Value;
+
         private readonly IAPIProvider api;
         private readonly NotificationsClientConnector connector;
 
diff --git a/osu.Game/Overlays/BeatmapListing/BeatmapSearchRulesetFilterRow.cs b/osu.Game/Overlays/BeatmapListing/BeatmapSearchRulesetFilterRow.cs
index fa37810f37..96626d0ac6 100644
--- a/osu.Game/Overlays/BeatmapListing/BeatmapSearchRulesetFilterRow.cs
+++ b/osu.Game/Overlays/BeatmapListing/BeatmapSearchRulesetFilterRow.cs
@@ -6,6 +6,7 @@
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Localisation;
+using osu.Game.Extensions;
 using osu.Game.Resources.Localisation.Web;
 using osu.Game.Rulesets;
 
@@ -28,7 +29,13 @@ namespace osu.Game.Overlays.BeatmapListing
                 AddTabItem(new RulesetFilterTabItemAny());
 
                 foreach (var r in rulesets.AvailableRulesets)
+                {
+                    // Don't display non-legacy rulesets
+                    if (!r.IsLegacyRuleset())
+                        continue;
+
                     AddItem(r);
+                }
             }
         }
 
diff --git a/osu.Game/Overlays/OverlayRulesetSelector.cs b/osu.Game/Overlays/OverlayRulesetSelector.cs
index bcce2ce433..9205a14d9f 100644
--- a/osu.Game/Overlays/OverlayRulesetSelector.cs
+++ b/osu.Game/Overlays/OverlayRulesetSelector.cs
@@ -13,6 +13,9 @@ namespace osu.Game.Overlays
 {
     public partial class OverlayRulesetSelector : RulesetSelector
     {
+        // Since this component is used in online overlays and currently web-side doesn't support non-legacy rulesets, let's disable them for now.
+        protected override bool LegacyOnly => true;
+
         public OverlayRulesetSelector()
         {
             AutoSizeAxes = Axes.Both;
diff --git a/osu.Game/Overlays/Settings/Sections/Graphics/RendererSettings.cs b/osu.Game/Overlays/Settings/Sections/Graphics/RendererSettings.cs
index 775606caf0..a5fdfdc105 100644
--- a/osu.Game/Overlays/Settings/Sections/Graphics/RendererSettings.cs
+++ b/osu.Game/Overlays/Settings/Sections/Graphics/RendererSettings.cs
@@ -27,7 +27,8 @@ namespace osu.Game.Overlays.Settings.Sections.Graphics
                 new SettingsEnumDropdown<FrameSync>
                 {
                     LabelText = GraphicsSettingsStrings.FrameLimiter,
-                    Current = config.GetBindable<FrameSync>(FrameworkSetting.FrameSync)
+                    Current = config.GetBindable<FrameSync>(FrameworkSetting.FrameSync),
+                    Keywords = new[] { @"fps" },
                 },
                 new SettingsEnumDropdown<ExecutionMode>
                 {
diff --git a/osu.Game/Overlays/Volume/MuteButton.cs b/osu.Game/Overlays/Volume/MuteButton.cs
index 9cc346a38b..c83ad4ac0d 100644
--- a/osu.Game/Overlays/Volume/MuteButton.cs
+++ b/osu.Game/Overlays/Volume/MuteButton.cs
@@ -88,5 +88,13 @@ namespace osu.Game.Overlays.Volume
         {
             Content.TransformTo<Container<Drawable>, ColourInfo>("BorderColour", unhoveredColour, 500, Easing.OutQuint);
         }
+
+        protected override bool OnMouseDown(MouseDownEvent e)
+        {
+            base.OnMouseDown(e);
+
+            // Block mouse down to avoid dismissing overlays sitting behind the mute button
+            return true;
+        }
     }
 }
diff --git a/osu.Game/Rulesets/RulesetSelector.cs b/osu.Game/Rulesets/RulesetSelector.cs
index 062f8d6450..ba10033a98 100644
--- a/osu.Game/Rulesets/RulesetSelector.cs
+++ b/osu.Game/Rulesets/RulesetSelector.cs
@@ -6,6 +6,7 @@
 using osu.Framework.Graphics.UserInterface;
 using osu.Framework.Allocation;
 using osu.Framework.Logging;
+using osu.Game.Extensions;
 
 namespace osu.Game.Rulesets
 {
@@ -16,11 +17,16 @@ namespace osu.Game.Rulesets
 
         protected override Dropdown<RulesetInfo> CreateDropdown() => null;
 
+        protected virtual bool LegacyOnly => false;
+
         [BackgroundDependencyLoader]
         private void load()
         {
             foreach (var ruleset in Rulesets.AvailableRulesets)
             {
+                if (!ruleset.IsLegacyRuleset() && LegacyOnly)
+                    continue;
+
                 try
                 {
                     AddItem(ruleset);
diff --git a/osu.Game/Screens/Edit/Components/BottomBarContainer.cs b/osu.Game/Screens/Edit/Components/BottomBarContainer.cs
index 32ec3b6833..0ba1ab9258 100644
--- a/osu.Game/Screens/Edit/Components/BottomBarContainer.cs
+++ b/osu.Game/Screens/Edit/Components/BottomBarContainer.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Framework.Audio.Track;
 using osu.Framework.Bindables;
diff --git a/osu.Game/Screens/Edit/Components/EditorSidebar.cs b/osu.Game/Screens/Edit/Components/EditorSidebar.cs
index cfcfcd75e6..9a8c5115dd 100644
--- a/osu.Game/Screens/Edit/Components/EditorSidebar.cs
+++ b/osu.Game/Screens/Edit/Components/EditorSidebar.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
diff --git a/osu.Game/Screens/Edit/Components/EditorSidebarSection.cs b/osu.Game/Screens/Edit/Components/EditorSidebarSection.cs
index 4e8c55efa1..279793c0a1 100644
--- a/osu.Game/Screens/Edit/Components/EditorSidebarSection.cs
+++ b/osu.Game/Screens/Edit/Components/EditorSidebarSection.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
diff --git a/osu.Game/Screens/Edit/Components/Menus/EditorScreenSwitcherControl.cs b/osu.Game/Screens/Edit/Components/Menus/EditorScreenSwitcherControl.cs
index e88138def4..3d51874082 100644
--- a/osu.Game/Screens/Edit/Components/Menus/EditorScreenSwitcherControl.cs
+++ b/osu.Game/Screens/Edit/Components/Menus/EditorScreenSwitcherControl.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Shapes;
@@ -38,7 +36,7 @@ namespace osu.Game.Screens.Edit.Components.Menus
             });
         }
 
-        protected override Dropdown<EditorScreenMode> CreateDropdown() => null;
+        protected override Dropdown<EditorScreenMode> CreateDropdown() => null!;
 
         protected override TabItem<EditorScreenMode> CreateTabItem(EditorScreenMode value) => new TabItem(value);
 
diff --git a/osu.Game/Screens/Edit/Components/PlaybackControl.cs b/osu.Game/Screens/Edit/Components/PlaybackControl.cs
index f403551a62..87cbcb8aff 100644
--- a/osu.Game/Screens/Edit/Components/PlaybackControl.cs
+++ b/osu.Game/Screens/Edit/Components/PlaybackControl.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System.Linq;
 using osuTK;
 using osuTK.Graphics;
@@ -25,10 +23,10 @@ namespace osu.Game.Screens.Edit.Components
 {
     public partial class PlaybackControl : BottomBarContainer
     {
-        private IconButton playButton;
+        private IconButton playButton = null!;
 
         [Resolved]
-        private EditorClock editorClock { get; set; }
+        private EditorClock editorClock { get; set; } = null!;
 
         private readonly BindableNumber<double> freqAdjust = new BindableDouble(1);
 
@@ -108,7 +106,7 @@ namespace osu.Game.Screens.Edit.Components
 
             protected override TabItem<double> CreateTabItem(double value) => new PlaybackTabItem(value);
 
-            protected override Dropdown<double> CreateDropdown() => null;
+            protected override Dropdown<double> CreateDropdown() => null!;
 
             public PlaybackTabControl()
             {
diff --git a/osu.Game/Screens/Edit/Components/RadioButtons/EditorRadioButton.cs b/osu.Game/Screens/Edit/Components/RadioButtons/EditorRadioButton.cs
index bfcc0084bd..65f3e41c13 100644
--- a/osu.Game/Screens/Edit/Components/RadioButtons/EditorRadioButton.cs
+++ b/osu.Game/Screens/Edit/Components/RadioButtons/EditorRadioButton.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System;
 using osu.Framework.Allocation;
 using osu.Framework.Extensions.Color4Extensions;
@@ -24,7 +22,7 @@ namespace osu.Game.Screens.Edit.Components.RadioButtons
         /// <summary>
         /// Invoked when this <see cref="EditorRadioButton"/> has been selected.
         /// </summary>
-        public Action<RadioButton> Selected;
+        public Action<RadioButton>? Selected;
 
         public readonly RadioButton Button;
 
@@ -33,10 +31,10 @@ namespace osu.Game.Screens.Edit.Components.RadioButtons
         private Color4 selectedBackgroundColour;
         private Color4 selectedIconColour;
 
-        private Drawable icon;
+        private Drawable icon = null!;
 
-        [Resolved(canBeNull: true)]
-        private EditorBeatmap editorBeatmap { get; set; }
+        [Resolved]
+        private EditorBeatmap? editorBeatmap { get; set; }
 
         public EditorRadioButton(RadioButton button)
         {
diff --git a/osu.Game/Screens/Edit/Components/RadioButtons/EditorRadioButtonCollection.cs b/osu.Game/Screens/Edit/Components/RadioButtons/EditorRadioButtonCollection.cs
index 92dd47dc81..4391729adc 100644
--- a/osu.Game/Screens/Edit/Components/RadioButtons/EditorRadioButtonCollection.cs
+++ b/osu.Game/Screens/Edit/Components/RadioButtons/EditorRadioButtonCollection.cs
@@ -1,8 +1,7 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
+using System;
 using System.Collections.Generic;
 using osu.Framework.Extensions.IEnumerableExtensions;
 using osu.Framework.Graphics;
@@ -13,7 +12,7 @@ namespace osu.Game.Screens.Edit.Components.RadioButtons
 {
     public partial class EditorRadioButtonCollection : CompositeDrawable
     {
-        private IReadOnlyList<RadioButton> items;
+        private IReadOnlyList<RadioButton> items = Array.Empty<RadioButton>();
 
         public IReadOnlyList<RadioButton> Items
         {
@@ -45,7 +44,7 @@ namespace osu.Game.Screens.Edit.Components.RadioButtons
             };
         }
 
-        private RadioButton currentlySelected;
+        private RadioButton? currentlySelected;
 
         private void addButton(RadioButton button)
         {
diff --git a/osu.Game/Screens/Edit/Components/RadioButtons/RadioButton.cs b/osu.Game/Screens/Edit/Components/RadioButtons/RadioButton.cs
index 03745ce19d..9dcd29bf83 100644
--- a/osu.Game/Screens/Edit/Components/RadioButtons/RadioButton.cs
+++ b/osu.Game/Screens/Edit/Components/RadioButtons/RadioButton.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -24,11 +22,11 @@ namespace osu.Game.Screens.Edit.Components.RadioButtons
         /// <summary>
         /// A function which creates a drawable icon to represent this item. If null, a sane default should be used.
         /// </summary>
-        public readonly Func<Drawable> CreateIcon;
+        public readonly Func<Drawable>? CreateIcon;
 
-        private readonly Action action;
+        private readonly Action? action;
 
-        public RadioButton(string label, Action action, Func<Drawable> createIcon = null)
+        public RadioButton(string label, Action? action, Func<Drawable>? createIcon = null)
         {
             Label = label;
             CreateIcon = createIcon;
diff --git a/osu.Game/Screens/Edit/Components/TernaryButtons/DrawableTernaryButton.cs b/osu.Game/Screens/Edit/Components/TernaryButtons/DrawableTernaryButton.cs
index 45b7cd1b7c..873551db77 100644
--- a/osu.Game/Screens/Edit/Components/TernaryButtons/DrawableTernaryButton.cs
+++ b/osu.Game/Screens/Edit/Components/TernaryButtons/DrawableTernaryButton.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Framework.Extensions.Color4Extensions;
 using osu.Framework.Graphics;
@@ -23,7 +21,7 @@ namespace osu.Game.Screens.Edit.Components.TernaryButtons
         private Color4 selectedBackgroundColour;
         private Color4 selectedIconColour;
 
-        private Drawable icon;
+        private Drawable icon = null!;
 
         public readonly TernaryButton Button;
 
diff --git a/osu.Game/Screens/Edit/Components/TernaryButtons/TernaryButton.cs b/osu.Game/Screens/Edit/Components/TernaryButtons/TernaryButton.cs
index 8eb781c947..0ff2aa83b5 100644
--- a/osu.Game/Screens/Edit/Components/TernaryButtons/TernaryButton.cs
+++ b/osu.Game/Screens/Edit/Components/TernaryButtons/TernaryButton.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -19,9 +17,9 @@ namespace osu.Game.Screens.Edit.Components.TernaryButtons
         /// <summary>
         /// A function which creates a drawable icon to represent this item. If null, a sane default should be used.
         /// </summary>
-        public readonly Func<Drawable> CreateIcon;
+        public readonly Func<Drawable>? CreateIcon;
 
-        public TernaryButton(Bindable<TernaryState> bindable, string description, Func<Drawable> createIcon = null)
+        public TernaryButton(Bindable<TernaryState> bindable, string description, Func<Drawable>? createIcon = null)
         {
             Bindable = bindable;
             Description = description;
diff --git a/osu.Game/Screens/Edit/Components/TimeInfoContainer.cs b/osu.Game/Screens/Edit/Components/TimeInfoContainer.cs
index 1c16671ce4..9c51258f17 100644
--- a/osu.Game/Screens/Edit/Components/TimeInfoContainer.cs
+++ b/osu.Game/Screens/Edit/Components/TimeInfoContainer.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Graphics;
 using osu.Game.Graphics.Sprites;
 using osu.Framework.Allocation;
@@ -15,14 +13,14 @@ namespace osu.Game.Screens.Edit.Components
 {
     public partial class TimeInfoContainer : BottomBarContainer
     {
-        private OsuSpriteText trackTimer;
-        private OsuSpriteText bpm;
+        private OsuSpriteText trackTimer = null!;
+        private OsuSpriteText bpm = null!;
 
         [Resolved]
-        private EditorBeatmap editorBeatmap { get; set; }
+        private EditorBeatmap editorBeatmap { get; set; } = null!;
 
         [Resolved]
-        private EditorClock editorClock { get; set; }
+        private EditorClock editorClock { get; set; } = null!;
 
         [BackgroundDependencyLoader]
         private void load(OsuColour colours, OverlayColourProvider colourProvider)
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/BookmarkPart.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/BookmarkPart.cs
index f1023ade8c..3102bf7c06 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/BookmarkPart.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/BookmarkPart.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Game.Graphics;
 using osu.Game.Screens.Edit.Components.Timelines.Summary.Visualisations;
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/BreakPart.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/BreakPart.cs
index de5d074c51..e502dd951b 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/BreakPart.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/BreakPart.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Game.Beatmaps.Timing;
 using osu.Game.Graphics;
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/ControlPointPart.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/ControlPointPart.cs
index 111ba0b732..6f53f710ba 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/ControlPointPart.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/ControlPointPart.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System;
 using System.Collections.Specialized;
 using System.Diagnostics;
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/ControlPointVisualisation.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/ControlPointVisualisation.cs
index aa494271f8..12620963e1 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/ControlPointVisualisation.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/ControlPointVisualisation.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Game.Beatmaps.ControlPoints;
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/GroupVisualisation.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/GroupVisualisation.cs
index 64c0745596..b39365277f 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/GroupVisualisation.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/GroupVisualisation.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System.Linq;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/IControlPointVisualisation.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/IControlPointVisualisation.cs
index b9e2a969a5..c81f1828f7 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/IControlPointVisualisation.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/IControlPointVisualisation.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Game.Beatmaps.ControlPoints;
 
 namespace osu.Game.Screens.Edit.Components.Timelines.Summary.Parts
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/MarkerPart.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/MarkerPart.cs
index 5be6db55a4..d42c02e03d 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/MarkerPart.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/MarkerPart.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System;
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
@@ -20,10 +18,10 @@ namespace osu.Game.Screens.Edit.Components.Timelines.Summary.Parts
     /// </summary>
     public partial class MarkerPart : TimelinePart
     {
-        private Drawable marker;
+        private Drawable marker = null!;
 
         [Resolved]
-        private EditorClock editorClock { get; set; }
+        private EditorClock editorClock { get; set; } = null!;
 
         [BackgroundDependencyLoader]
         private void load()
@@ -44,7 +42,7 @@ namespace osu.Game.Screens.Edit.Components.Timelines.Summary.Parts
             return true;
         }
 
-        private ScheduledDelegate scheduledSeek;
+        private ScheduledDelegate? scheduledSeek;
 
         /// <summary>
         /// Seeks the <see cref="SummaryTimeline"/> to the time closest to a position on the screen relative to the <see cref="SummaryTimeline"/>.
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/TimelinePart.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/TimelinePart.cs
index e380a2063b..ee7e759ebc 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/TimelinePart.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/Parts/TimelinePart.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System;
 using osu.Framework.Allocation;
 using osu.Framework.Audio.Track;
@@ -26,7 +24,7 @@ namespace osu.Game.Screens.Edit.Components.Timelines.Summary.Parts
         private readonly IBindable<WorkingBeatmap> beatmap = new Bindable<WorkingBeatmap>();
 
         [Resolved]
-        protected EditorBeatmap EditorBeatmap { get; private set; }
+        protected EditorBeatmap EditorBeatmap { get; private set; } = null!;
 
         protected readonly IBindable<Track> Track = new Bindable<Track>();
 
@@ -34,7 +32,7 @@ namespace osu.Game.Screens.Edit.Components.Timelines.Summary.Parts
 
         protected override Container<T> Content => content;
 
-        public TimelinePart(Container<T> content = null)
+        public TimelinePart(Container<T>? content = null)
         {
             AddInternal(this.content = content ?? new Container<T> { RelativeSizeAxes = Axes.Both });
 
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/SummaryTimeline.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/SummaryTimeline.cs
index 075d47d82e..6199cefb57 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/SummaryTimeline.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/SummaryTimeline.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/TestGameplayButton.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/TestGameplayButton.cs
index a3a003947c..9b45464e81 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/TestGameplayButton.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/TestGameplayButton.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Sprites;
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/Visualisations/DurationVisualisation.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/Visualisations/DurationVisualisation.cs
index 6fc994b8b1..bfb50a05ea 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/Visualisations/DurationVisualisation.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/Visualisations/DurationVisualisation.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Shapes;
 
diff --git a/osu.Game/Screens/Edit/Components/Timelines/Summary/Visualisations/PointVisualisation.cs b/osu.Game/Screens/Edit/Components/Timelines/Summary/Visualisations/PointVisualisation.cs
index 75dacdf3e7..3f0c125ada 100644
--- a/osu.Game/Screens/Edit/Components/Timelines/Summary/Visualisations/PointVisualisation.cs
+++ b/osu.Game/Screens/Edit/Components/Timelines/Summary/Visualisations/PointVisualisation.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Shapes;
 
diff --git a/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineHitObjectBlueprint.cs b/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineHitObjectBlueprint.cs
index 03e67306df..4e5087c004 100644
--- a/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineHitObjectBlueprint.cs
+++ b/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineHitObjectBlueprint.cs
@@ -291,7 +291,7 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
             [Resolved]
             private Timeline timeline { get; set; } = null!;
 
-            [Resolved(CanBeNull = true)]
+            [Resolved]
             private IEditorChangeHandler? changeHandler { get; set; }
 
             private ScheduledDelegate? dragOperation;