A few xmldoc additions/fixes.

osu.Game/Beatmaps/IBeatmapConverter.cs

@@ -30,9 +30,9 @@ namespace osu.Game.Beatmaps
     public static class BeatmapConverterExtensions
     {
         /// <summary>
-        /// Checks if a Beatmap can be converted using a Beatmap Converter.
+        /// Checks if a Beatmap can be converted using this Beatmap Converter.
         /// </summary>
-        /// <param name="converter">The Converter to use.</param>
+        /// <param name="converter">The Beatmap Converter.</param>
         /// <param name="beatmap">The Beatmap to check.</param>
         /// <returns>Whether the Beatmap can be converted using <paramref name="converter"/>.</returns>
         public static bool CanConvert<TObject>(this IBeatmapConverter<TObject> converter, Beatmap beatmap) where TObject : HitObject

osu.Game/Modes/Objects/Legacy/Catch/Hit.cs

@@ -6,7 +6,7 @@ using osu.Game.Modes.Objects.Types;
 namespace osu.Game.Modes.Objects.Legacy.Catch
 {
     /// <summary>
-    /// Legacy Hit-type, used for parsing Beatmaps.
+    /// Legacy osu!catch Hit-type, used for parsing Beatmaps.
     /// </summary>
     internal sealed class Hit : HitObject, IHasCombo, IHasXPosition
     {

osu.Game/Modes/Objects/Legacy/Catch/HitObjectParser.cs

@@ -1,12 +1,15 @@
 // Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
-using System.Collections.Generic;
 using OpenTK;
 using osu.Game.Modes.Objects.Types;
+using System.Collections.Generic;
 
 namespace osu.Game.Modes.Objects.Legacy.Catch
 {
+    /// <summary>
+    /// A HitObjectParser to parse legacy osu!catch Beatmaps.
+    /// </summary>
     internal class HitObjectParser : Legacy.HitObjectParser
     {
         protected override HitObject CreateHit(Vector2 position, bool newCombo)

osu.Game/Modes/Objects/Legacy/Catch/Slider.cs

@@ -6,7 +6,7 @@ using osu.Game.Modes.Objects.Types;
 namespace osu.Game.Modes.Objects.Legacy.Catch
 {
     /// <summary>
-    /// Legacy Slider-type, used for parsing Beatmaps.
+    /// Legacy osu!catch Slider-type, used for parsing Beatmaps.
     /// </summary>
     internal sealed class Slider : CurvedHitObject, IHasXPosition, IHasCombo
     {

osu.Game/Modes/Objects/Legacy/Catch/Spinner.cs

@@ -6,9 +6,9 @@ using osu.Game.Modes.Objects.Types;
 namespace osu.Game.Modes.Objects.Legacy.Catch
 {
     /// <summary>
-    /// Legacy Spinner-type, used for parsing Beatmaps.
+    /// Legacy osu!catch Spinner-type, used for parsing Beatmaps.
     /// </summary>
-    internal class Spinner : HitObject, IHasEndTime
+    internal sealed class Spinner : HitObject, IHasEndTime
     {
         public double EndTime { get; set; }
 

osu.Game/Modes/Objects/Legacy/HitObjectParser.cs

@@ -11,6 +11,9 @@ using osu.Game.Audio;
 
 namespace osu.Game.Modes.Objects.Legacy
 {
+    /// <summary>
+    /// A HitObjectParser to parse legacy Beatmaps.
+    /// </summary>
     internal abstract class HitObjectParser : Objects.HitObjectParser
     {
         public override HitObject Parse(string text)
@@ -146,10 +149,6 @@ namespace osu.Game.Modes.Objects.Legacy
             return result;
         }
 
-        protected abstract HitObject CreateHit(Vector2 position, bool newCombo);
-        protected abstract HitObject CreateSlider(Vector2 position, bool newCombo, List<Vector2> controlPoints, double length, CurveType curveType, int repeatCount);
-        protected abstract HitObject CreateSpinner(Vector2 position, double endTime);
-
         private void readCustomSampleBanks(string str, ref string normalSampleBank, ref string addSampleBank, ref int sampleVolume)
         {
             if (string.IsNullOrEmpty(str))
@@ -175,6 +174,34 @@ namespace osu.Game.Modes.Objects.Legacy
             sampleVolume = split.Length > 3 ? int.Parse(split[3]) : 0;
         }
 
+        /// <summary>
+        /// Creates a legacy Hit-type hit object.
+        /// </summary>
+        /// <param name="position">The position of the hit object.</param>
+        /// <param name="newCombo">Whether the hit object creates a new combo.</param>
+        /// <returns>The hit object.</returns>
+        protected abstract HitObject CreateHit(Vector2 position, bool newCombo);
+
+        /// <summary>
+        /// Creats a legacy Slider-type hit object.
+        /// </summary>
+        /// <param name="position">The position of the hit object.</param>
+        /// <param name="newCombo">Whether the hit object creates a new combo.</param>
+        /// <param name="controlPoints">The slider control points.</param>
+        /// <param name="length">The slider length.</param>
+        /// <param name="curveType">The slider curve type.</param>
+        /// <param name="repeatCount">The slider repeat count.</param>
+        /// <returns>The hit object.</returns>
+        protected abstract HitObject CreateSlider(Vector2 position, bool newCombo, List<Vector2> controlPoints, double length, CurveType curveType, int repeatCount);
+
+        /// <summary>
+        /// Creates a legacy Spinner-type hit object.
+        /// </summary>
+        /// <param name="position">The position of the hit object.</param>
+        /// <param name="endTime">The spinner end time.</param>
+        /// <returns>The hit object.</returns>
+        protected abstract HitObject CreateSpinner(Vector2 position, double endTime);
+
         [Flags]
         private enum LegacySoundType
         {

osu.Game/Modes/Objects/Legacy/Mania/Hit.cs

@@ -6,7 +6,7 @@ using osu.Game.Modes.Objects.Types;
 namespace osu.Game.Modes.Objects.Legacy.Mania
 {
     /// <summary>
-    /// Legacy Hit-type, used for parsing Beatmaps.
+    /// Legacy osu!mania Hit-type, used for parsing Beatmaps.
     /// </summary>
     internal sealed class Hit : HitObject, IHasColumn, IHasCombo
     {

osu.Game/Modes/Objects/Legacy/Mania/HitObjectParser.cs

@@ -1,12 +1,15 @@
 // Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
-using System.Collections.Generic;
 using OpenTK;
 using osu.Game.Modes.Objects.Types;
+using System.Collections.Generic;
 
 namespace osu.Game.Modes.Objects.Legacy.Mania
 {
+    /// <summary>
+    /// A HitObjectParser to parse legacy osu!mania Beatmaps.
+    /// </summary>
     internal class HitObjectParser : Legacy.HitObjectParser
     {
         protected override HitObject CreateHit(Vector2 position, bool newCombo)

osu.Game/Modes/Objects/Legacy/Mania/Slider.cs

@@ -6,7 +6,7 @@ using osu.Game.Modes.Objects.Types;
 namespace osu.Game.Modes.Objects.Legacy.Mania
 {
     /// <summary>
-    /// Legacy Slider-type, used for parsing Beatmaps.
+    /// Legacy osu!mania Slider-type, used for parsing Beatmaps.
     /// </summary>
     internal sealed class Slider : CurvedHitObject, IHasColumn, IHasCombo
     {

osu.Game/Modes/Objects/Legacy/Mania/Spinner.cs

@@ -6,9 +6,9 @@ using osu.Game.Modes.Objects.Types;
 namespace osu.Game.Modes.Objects.Legacy.Mania
 {
     /// <summary>
-    /// Legacy Spinner-type, used for parsing Beatmaps.
+    /// Legacy osu!mania Spinner-type, used for parsing Beatmaps.
     /// </summary>
-    internal class Spinner : HitObject, IHasEndTime, IHasColumn
+    internal sealed class Spinner : HitObject, IHasEndTime, IHasColumn
     {
         public double EndTime { get; set; }
 

osu.Game/Modes/Objects/Legacy/Osu/Hit.cs

@@ -7,7 +7,7 @@ using OpenTK;
 namespace osu.Game.Modes.Objects.Legacy.Osu
 {
     /// <summary>
-    /// Legacy Hit-type, used for parsing Beatmaps.
+    /// Legacy osu! Hit-type, used for parsing Beatmaps.
     /// </summary>
     internal sealed class Hit : HitObject, IHasPosition, IHasCombo
     {

osu.Game/Modes/Objects/Legacy/Osu/HitObjectParser.cs

@@ -7,6 +7,9 @@ using System.Collections.Generic;
 
 namespace osu.Game.Modes.Objects.Legacy.Osu
 {
+    /// <summary>
+    /// A HitObjectParser to parse legacy osu! Beatmaps.
+    /// </summary>
     internal class HitObjectParser : Legacy.HitObjectParser
     {
         protected override HitObject CreateHit(Vector2 position, bool newCombo)

osu.Game/Modes/Objects/Legacy/Osu/Slider.cs

@@ -7,7 +7,7 @@ using OpenTK;
 namespace osu.Game.Modes.Objects.Legacy.Osu
 {
     /// <summary>
-    /// Legacy Slider-type, used for parsing Beatmaps.
+    /// Legacy osu! Slider-type, used for parsing Beatmaps.
     /// </summary>
     internal sealed class Slider : CurvedHitObject, IHasPosition, IHasCombo
     {

osu.Game/Modes/Objects/Legacy/Osu/Spinner.cs

@@ -7,9 +7,9 @@ using OpenTK;
 namespace osu.Game.Modes.Objects.Legacy.Osu
 {
     /// <summary>
-    /// Legacy Spinner-type, used for parsing Beatmaps.
+    /// Legacy osu! Spinner-type, used for parsing Beatmaps.
     /// </summary>
-    internal class Spinner : HitObject, IHasEndTime, IHasPosition
+    internal sealed class Spinner : HitObject, IHasEndTime, IHasPosition
     {
         public double EndTime { get; set; }
 

osu.Game/Modes/Objects/Legacy/Taiko/Hit.cs

@@ -6,7 +6,7 @@ using osu.Game.Modes.Objects.Types;
 namespace osu.Game.Modes.Objects.Legacy.Taiko
 {
     /// <summary>
-    /// Legacy Hit-type, used for parsing Beatmaps.
+    /// Legacy osu!taiko Hit-type, used for parsing Beatmaps.
     /// </summary>
     internal sealed class Hit : HitObject, IHasCombo
     {

osu.Game/Modes/Objects/Legacy/Taiko/HitObjectParser.cs

@@ -7,6 +7,9 @@ using System.Collections.Generic;
 
 namespace osu.Game.Modes.Objects.Legacy.Taiko
 {
+    /// <summary>
+    /// A HitObjectParser to parse legacy osu!taiko Beatmaps.
+    /// </summary>
     internal class HitObjectParser : Legacy.HitObjectParser
     {
         protected override HitObject CreateHit(Vector2 position, bool newCombo)

osu.Game/Modes/Objects/Legacy/Taiko/Slider.cs

@@ -6,7 +6,7 @@ using osu.Game.Modes.Objects.Types;
 namespace osu.Game.Modes.Objects.Legacy.Taiko
 {
     /// <summary>
-    /// Legacy Slider-type, used for parsing Beatmaps.
+    /// Legacy osu!taiko Slider-type, used for parsing Beatmaps.
     /// </summary>
     internal sealed class Slider : CurvedHitObject, IHasCombo
     {

osu.Game/Modes/Objects/Legacy/Taiko/Spinner.cs

@@ -6,9 +6,9 @@ using osu.Game.Modes.Objects.Types;
 namespace osu.Game.Modes.Objects.Legacy.Taiko
 {
     /// <summary>
-    /// Legacy Spinner-type, used for parsing Beatmaps.
+    /// Legacy osu!taiko Spinner-type, used for parsing Beatmaps.
     /// </summary>
-    internal class Spinner : HitObject, IHasEndTime
+    internal sealed class Spinner : HitObject, IHasEndTime
     {
         public double EndTime { get; set; }
 

osu.Game/Modes/Objects/Types/IHasColumn.cs

@@ -3,8 +3,14 @@
 
 namespace osu.Game.Modes.Objects.Types
 {
+    /// <summary>
+    /// A HitObject that lies in a column space.
+    /// </summary>
     public interface IHasColumn
     {
+        /// <summary>
+        /// The column which this HitObject lies in.
+        /// </summary>
         int Column { get; }
     }
 }

osu.Game/Modes/Objects/Types/IHasXPosition.cs

@@ -9,6 +9,9 @@ namespace osu.Game.Modes.Objects.Types
     /// </summary>
     public interface IHasXPosition
     {
+        /// <summary>
+        /// The starting X-position of this HitObject.
+        /// </summary>
         float X { get; }
     }
 }

osu.Game/Modes/Objects/Types/IHasYPosition.cs

@@ -9,6 +9,9 @@ namespace osu.Game.Modes.Objects.Types
     /// </summary>
     public interface IHasYPosition
     {
+        /// <summary>
+        /// The starting Y-position of this HitObject.
+        /// </summary>
         float Y { get; }
     }
 }