diff --git a/Shared/Debug.cs b/Shared/Debug.cs
index 6241e38..9927bc3 100644
--- a/Shared/Debug.cs
+++ b/Shared/Debug.cs
@@ -68,7 +68,7 @@ namespace SemiColinGames {
       rects.Add(new DebugRect(rect, color));
     }
 
-    public static void AddRect(Aabb box, Color color) {
+    public static void AddRect(AABB box, Color color) {
       Rectangle rect = new Rectangle(
           (int) (box.Position.X - box.HalfSize.X), (int) (box.Position.Y - box.HalfSize.Y),
           (int) (box.HalfSize.X * 2), (int) (box.HalfSize.Y * 2));
diff --git a/Shared/Geometry.cs b/Shared/Geometry.cs
index 085e144..ccb1545 100644
--- a/Shared/Geometry.cs
+++ b/Shared/Geometry.cs
@@ -6,17 +6,17 @@ using System;
 namespace SemiColinGames {
 
   public readonly struct Hit {
-    public readonly Aabb Collider;
+    public readonly AABB Collider;
     public readonly Vector2 Position;
     public readonly Vector2 Delta;
     public readonly Vector2 Normal;
     public readonly float Time;  // ranges from [0, 1].
 
-    public Hit(Aabb collider, Vector2 position, Vector2 delta, Vector2 normal) :
+    public Hit(AABB collider, Vector2 position, Vector2 delta, Vector2 normal) :
       this(collider, position, delta, normal, 0.0f) {
     }
 
-    public Hit(Aabb collider, Vector2 position, Vector2 delta, Vector2 normal, float time) {
+    public Hit(AABB collider, Vector2 position, Vector2 delta, Vector2 normal, float time) {
       Collider = collider;
       Position = position;
       Delta = delta;
@@ -37,7 +37,7 @@ namespace SemiColinGames {
     }
   }
 
-  public readonly struct Aabb {
+  public readonly struct AABB {
     public readonly Vector2 Position;  // centroid
     public readonly Vector2 HalfSize;
 
@@ -51,12 +51,12 @@ namespace SemiColinGames {
       }
     }
 
-    public Aabb(Vector2 position, Vector2 halfSize) {
+    public AABB(Vector2 position, Vector2 halfSize) {
       Position = position;
       HalfSize = halfSize;
     }
 
-    public Hit? Intersect(Aabb box) {
+    public Hit? Intersect(AABB box) {
       float dx = box.Position.X - Position.X;
       float px = box.HalfSize.X + HalfSize.X - Math.Abs(dx);
       if (px <= 0) {
@@ -121,7 +121,7 @@ namespace SemiColinGames {
       return new Hit(this, hitPos, hitDelta, normal, hitTime);
     }
 
-    public Sweep Sweep(Aabb box, Vector2 delta) {
+    public Sweep Sweep(AABB box, Vector2 delta) {
       // fast-path case if the other box is static
       if (delta.X == 0 && delta.Y == 0) {
         Hit? staticHit = Intersect(box);
diff --git a/Shared/Player.cs b/Shared/Player.cs
index 2aa8d5a..12e156d 100644
--- a/Shared/Player.cs
+++ b/Shared/Player.cs
@@ -46,25 +46,26 @@ namespace SemiColinGames {
 
     public Point Position { get { return position; } }
 
-    public void Update(float modelTime, History<Input> input, Aabb[] collisionTargets) {
-      Aabb BoxOffset(Point position, int yOffset) {
-        return new Aabb(new Vector2(position.X, position.Y + yOffset), halfSize);
+    public void Update(float modelTime, History<Input> input, AABB[] collisionTargets) {
+      AABB BoxOffset(Point position, int yOffset) {
+        return new AABB(new Vector2(position.X, position.Y + yOffset), halfSize);
       }
 
-      Aabb Box(Point position) {
+      AABB Box(Point position) {
         return BoxOffset(position, 0);
       }
 
       Vector2 movement = HandleInput(modelTime, input);
 
       // Broad test: remove all collision targets nowhere near the player.
-      var candidates = new List<Aabb>();
+      // TODO: don't allocate a list here.
+      var candidates = new List<AABB>();
       // Expand the box in the direction of movement. The center is the midpoint of the line
       // between the player's current position and their desired movement. The width increases by
       // the magnitude of the movement in each direction. We add 1 to each dimension just to be
       // sure (the only downside is a small number of false-positive AABBs, which should be
       // discarded by later tests anyhow.)
-      Aabb largeBox = new Aabb(
+      AABB largeBox = new AABB(
         new Vector2(position.X + movement.X / 2, position.Y + movement.Y / 2),
         new Vector2(halfSize.X + Math.Abs(movement.X) + 1, halfSize.Y + Math.Abs(movement.Y) + 1));
       foreach (var box in collisionTargets) {
@@ -80,7 +81,7 @@ namespace SemiColinGames {
         int dy = movePoints[i].Y - movePoints[i - 1].Y;
         if (dy != 0) {
           Point newPosition = new Point(position.X, position.Y + dy);
-          Aabb player = Box(newPosition);
+          AABB player = Box(newPosition);
           bool reject = false;
           foreach (var box in candidates) {
             if (box.Intersect(player) != null) {
@@ -94,7 +95,7 @@ namespace SemiColinGames {
         }
         if (dx != 0) {
           Point newPosition = new Point(position.X + dx, position.Y);
-          Aabb player = Box(newPosition);
+          AABB player = Box(newPosition);
           bool reject = false;
           foreach (var box in candidates) {
             if (box.Intersect(player) != null) {
@@ -109,7 +110,7 @@ namespace SemiColinGames {
       }
 
       bool standingOnGround = false;
-      Aabb groundIntersect = BoxOffset(position, 1);
+      AABB groundIntersect = BoxOffset(position, 1);
       foreach (var box in candidates) {
         if (groundIntersect.Intersect(box) != null) {
           standingOnGround = true;
diff --git a/Shared/World.cs b/Shared/World.cs
index 5f9f3b6..c1519ad 100644
--- a/Shared/World.cs
+++ b/Shared/World.cs
@@ -166,21 +166,21 @@ namespace SemiColinGames {
       // Because we added tiles from left to right, the CollisionTargets are sorted by x-position.
       // We maintain this invariant so that it's possible to efficiently find CollisionTargets that
       // are nearby a given x-position.
-      CollisionTargets = new Aabb[tiles.Length + 2];
+      CollisionTargets = new AABB[tiles.Length + 2];
 
       // Add a synthetic collisionTarget on the left side of the world.
-      CollisionTargets[0] = new Aabb(new Vector2(-1, 0), new Vector2(1, float.MaxValue));
+      CollisionTargets[0] = new AABB(new Vector2(-1, 0), new Vector2(1, float.MaxValue));
 
       // Now add all the normal collisionTargets for every static terrain tile.
       Vector2 halfSize = new Vector2(TileSize / 2, TileSize / 2);
       for (int i = 0; i < tiles.Length; i++) {
         Vector2 center = new Vector2(
           tiles[i].Position.Left + halfSize.X, tiles[i].Position.Top + halfSize.Y);
-        CollisionTargets[i + 1] = new Aabb(center, halfSize);
+        CollisionTargets[i + 1] = new AABB(center, halfSize);
       }
 
       // Add a final synthetic collisionTarget on the right side of the world.
-      CollisionTargets[tiles.Length + 1] = new Aabb(
+      CollisionTargets[tiles.Length + 1] = new AABB(
           new Vector2(Width + 1, 0), new Vector2(1, float.MaxValue));
     }
 
@@ -190,6 +190,6 @@ namespace SemiColinGames {
       }
     }
 
-    public Aabb[] CollisionTargets { get; }
+    public AABB[] CollisionTargets { get; }
   }
 }
diff --git a/SharedTests/GeometryTests.cs b/SharedTests/GeometryTests.cs
index f1f9e92..4ae36f2 100644
--- a/SharedTests/GeometryTests.cs
+++ b/SharedTests/GeometryTests.cs
@@ -7,13 +7,13 @@ namespace SemiColinGames.Tests {
   public class GeometryTests {
     [TestMethod]
     public void TestIntersectSegmentNotColliding() {
-      Aabb box = new Aabb(new Vector2(0, 0), new Vector2(8, 8));
+      AABB box = new AABB(new Vector2(0, 0), new Vector2(8, 8));
       Assert.IsNull(box.IntersectSegment(new Vector2(-16, -16), new Vector2(32, 0)));
     }
 
     [TestMethod]
     public void TestIntersectSegmentHit() {
-      Aabb box = new Aabb(new Vector2(0, 0), new Vector2(8, 8));
+      AABB box = new AABB(new Vector2(0, 0), new Vector2(8, 8));
       var point = new Vector2(-16, 4);
       var delta = new Vector2(32, 0);
       Hit? maybeHit = box.IntersectSegment(point, delta);
@@ -36,7 +36,7 @@ namespace SemiColinGames.Tests {
 
     [TestMethod]
     public void TestIntersectSegmentFromInsideBox() {
-      Aabb box = new Aabb(new Vector2(0, 0), new Vector2(8, 8));
+      AABB box = new AABB(new Vector2(0, 0), new Vector2(8, 8));
       var point = new Vector2(-4, 4);
       var delta = new Vector2(32, 0);
       Hit? maybeHit = box.IntersectSegment(point, delta);
@@ -59,7 +59,7 @@ namespace SemiColinGames.Tests {
 
     [TestMethod]
     public void TestIntersectSegmentWithPadding() {
-      Aabb box = new Aabb(new Vector2(0, 0), new Vector2(8, 8));
+      AABB box = new AABB(new Vector2(0, 0), new Vector2(8, 8));
       var point = new Vector2(-16, 4);
       var delta = new Vector2(32, 0);
       int padding = 4;
@@ -83,7 +83,7 @@ namespace SemiColinGames.Tests {
 
     [TestMethod]
     public void TestIntersectSegmentFromTwoDirections() {
-      Aabb box = new Aabb(new Vector2(0, 0), new Vector2(32, 32));
+      AABB box = new AABB(new Vector2(0, 0), new Vector2(32, 32));
       var farPos = new Vector2(64, 0);
       var farToNearDelta = new Vector2(-32, 0);
       Assert.IsNull(box.IntersectSegment(farPos, farToNearDelta));
@@ -95,7 +95,7 @@ namespace SemiColinGames.Tests {
 
     [TestMethod]
     public void TestIntersectSegmentXAxisAligned() {
-      Aabb box = new Aabb(new Vector2(0, 0), new Vector2(16, 16));
+      AABB box = new AABB(new Vector2(0, 0), new Vector2(16, 16));
       var pos = new Vector2(-32, 0);
       var delta = new Vector2(64, 0);
       Hit? maybeHit = box.IntersectSegment(pos, delta);
@@ -110,7 +110,7 @@ namespace SemiColinGames.Tests {
 
     [TestMethod]
     public void TestIntersectSegmentYAxisAligned() {
-      Aabb box = new Aabb(new Vector2(0, 0), new Vector2(16, 16));
+      AABB box = new AABB(new Vector2(0, 0), new Vector2(16, 16));
       var pos = new Vector2(0, -32);
       var delta = new Vector2(0, 64);
       Hit? maybeHit = box.IntersectSegment(pos, delta);