Implement the arrange mod.

osu.Game.Rulesets.Osu/Mods/OsuModArrange.cs

@@ -0,0 +1,56 @@
+using System;
+using System.Collections.Generic;
+using osu.Framework.Extensions.IEnumerableExtensions;
+using osu.Framework.Graphics;
+using osu.Game.Graphics;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.Objects.Drawables;
+using osu.Game.Rulesets.Osu.Objects;
+using OpenTK;
+
+namespace osu.Game.Rulesets.Osu.Mods
+{
+    internal class OsuModArrange : Mod, IApplicableToDrawableHitObjects
+    {
+        public override string Name => "Arrange";
+        public override string ShortenedName => "Arrange";
+        public override FontAwesome Icon => FontAwesome.fa_arrows;
+        public override ModType Type => ModType.DifficultyIncrease;
+        public override string Description => "Everything rotates. EVERYTHING";
+        public override bool Ranked => true;
+        public override double ScoreMultiplier => 1.05;
+
+        public void ApplyToDrawableHitObjects(IEnumerable<DrawableHitObject> drawables)
+        {
+            drawables.ForEach(drawable => drawable.ApplyCustomUpdateState += drawableOnApplyCustomUpdateState);
+        }
+
+        private float theta = 0;
+
+        private void drawableOnApplyCustomUpdateState(DrawableHitObject drawable, ArmedState state)
+        {
+            var hitObject = (OsuHitObject) drawable.HitObject;
+
+            Vector2 origPos;
+
+            if (hitObject is RepeatPoint rp)
+            {
+                return;
+            }
+            else
+            {
+                origPos = drawable.Position;
+            }
+
+            using (drawable.BeginAbsoluteSequence(hitObject.StartTime - hitObject.TimeFadeIn - 1000, true))
+            {
+                drawable
+                    .MoveToOffset(new Vector2((float)Math.Cos(theta), (float)Math.Sin(theta)) * 250)
+                    .MoveTo(origPos, hitObject.TimeFadeIn + 1000, Easing.InOutSine);
+            }
+
+            if (hitObject is HitCircle || hitObject is Slider)
+                theta += 0.4f;
+        }
+    }
+}

osu.Game.Rulesets.Osu/OsuRuleset.cs

@@ -103,6 +103,7 @@ public override IEnumerable<Mod> GetModsFor(ModType type)
                         new MultiMod(new OsuModDoubleTime(), new OsuModNightcore()),
                         new OsuModHidden(),
                         new OsuModFlashlight(),
+                        new OsuModArrange(), 
                     };
                 case ModType.Special:
                     return new Mod[]