diff --git a/Assets/Cryville/Common/Tweener.cs b/Assets/Cryville/Common/Tweener.cs
new file mode 100644
index 0000000..3a75c82
--- /dev/null
+++ b/Assets/Cryville/Common/Tweener.cs
@@ -0,0 +1,95 @@
+using System;
+
+namespace Cryville.Common {
+	public class PropertyTweener<T> {
+		readonly Func<T> _getter;
+		readonly Action<T> _setter;
+		readonly Tweener<T> _tweener;
+		public PropertyTweener(Func<T> getter, Action<T> setter, Tweener<T> tweener) {
+			_getter = getter;
+			_setter = setter;
+			_tweener = tweener;
+			var initialValue = getter();
+			_tweener.Start(initialValue, initialValue, float.Epsilon);
+		}
+		public PropertyTweener<T> Start(T endValue, float duration) {
+			_tweener.Start(_getter(), endValue, duration);
+			return this;
+		}
+		public void Advance(float deltaTime) {
+			if (!_tweener.Advance(deltaTime, out var value)) return;
+			_setter(value);
+		}
+	}
+	public delegate T Addition<T>(T a, T b);
+	public delegate T Multiplication<T>(float k, T b);
+	public delegate float EasingFunction(float t);
+	public class Tweener<T> {
+		readonly Addition<T> _addition;
+		readonly Multiplication<T> _multiplication;
+		public Tweener(Addition<T> addition, Multiplication<T> multiplication) {
+			_addition = addition;
+			_multiplication = multiplication;
+		}
+		public EasingFunction EasingFunction { get; set; } = EasingFunctions.Linear;
+		public Tweener<T> With(EasingFunction easing) {
+			EasingFunction = easing;
+			return this;
+		}
+
+		T _startValue = default;
+		T _endValue = default;
+		float _duration = float.Epsilon;
+		float _time;
+		bool _endOfTween;
+		public Tweener<T> Start(T startValue, T endValue, float duration) {
+			_startValue = startValue;
+			_endValue = endValue;
+			_duration = duration;
+			_time = 0;
+			_endOfTween = false;
+			return this;
+		}
+		public bool Advance(float deltaTime, out T value) {
+			if (_endOfTween) {
+				value = _endValue;
+				return false;
+			}
+			if (_time >= _duration) {
+				value = _endValue;
+				_endOfTween = true;
+				return true;
+			}
+			_time += deltaTime;
+			var ratio = EasingFunction(System.Math.Clamp(_time / _duration, 0, 1));
+			value = _addition(_multiplication(1 - ratio, _startValue), _multiplication(ratio, _endValue));
+			return true;
+		}
+		public Tweener<object> Boxed() {
+			return new Tweener<object>((a, b) => _addition((T)a, (T)b), (k, v) => _multiplication(k, (T)v));
+		}
+	}
+	public static class Tweeners {
+		public static Tweener<byte> Byte => new((a, b) => (byte)(a + b), (k, v) => (byte)(k * v));
+		public static Tweener<sbyte> SByte => new((a, b) => (sbyte)(a + b), (k, v) => (sbyte)(k * v));
+		public static Tweener<short> Int16 => new((a, b) => (short)(a + b), (k, v) => (short)(k * v));
+		public static Tweener<ushort> UInt16 => new((a, b) => (ushort)(a + b), (k, v) => (ushort)(k * v));
+		public static Tweener<int> Int32 => new((a, b) => a + b, (k, v) => (int)(k * v));
+		public static Tweener<uint> UInt32 => new((a, b) => a + b, (k, v) => (uint)(k * v));
+		public static Tweener<long> Int64 => new((a, b) => a + b, (k, v) => (long)(k * v));
+		public static Tweener<ulong> UInt64 => new((a, b) => a + b, (k, v) => (ulong)(k * v));
+		public static Tweener<IntPtr> IntPtr => new((a, b) => new IntPtr((long)a + (long)b), (k, v) => new IntPtr((long)(k * (long)v)));
+		public static Tweener<UIntPtr> UIntPtr => new((a, b) => new UIntPtr((ulong)a + (ulong)b), (k, v) => new UIntPtr((ulong)(k * (ulong)v)));
+		public static Tweener<float> Float => new((a, b) => a + b, (k, v) => k * v);
+		public static Tweener<double> Double => new((a, b) => a + b, (k, v) => k * v);
+	}
+	public static class EasingFunctions {
+		public static float Linear(float x) => x;
+		public static float InQuad(float x) => x * x;
+		public static float InCubic(float x) => x * x * x;
+		public static float InSine(float x) => 1 - OutSine(1 - x);
+		public static float OutQuad(float x) => 1 - InQuad(1 - x);
+		public static float OutCubic(float x) => 1 - InCubic(1 - x);
+		public static float OutSine(float x) => MathF.Sin(x * MathF.PI / 2);
+	}
+}
diff --git a/Assets/Cryville/Common/Tweener.cs.meta b/Assets/Cryville/Common/Tweener.cs.meta
new file mode 100644
index 0000000..c6db865
--- /dev/null
+++ b/Assets/Cryville/Common/Tweener.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 0b4037ba4138aae47b8da984f30b4db9
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Assets/Cryville/Common/Unity/StateTweener.cs b/Assets/Cryville/Common/Unity/StateTweener.cs
new file mode 100644
index 0000000..c75af96
--- /dev/null
+++ b/Assets/Cryville/Common/Unity/StateTweener.cs
@@ -0,0 +1,181 @@
+using Cryville.Common.Reflection;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using UnityEngine;
+
+namespace Cryville.Common.Unity {
+	public class StateTweener : MonoBehaviour {
+		[SerializeField]
+		State[] m_states;
+		[Serializable]
+		struct State {
+			[SerializeField]
+			public string Name;
+			[SerializeField]
+			public AttributeState[] Attributes;
+		}
+		[Serializable]
+		struct AttributeState {
+			[SerializeField]
+			public AttributeBinding Attribute;
+			[SerializeField]
+			public string Value;
+		}
+		[Serializable]
+		struct AttributeBinding : IEquatable<AttributeBinding> {
+			[SerializeField]
+			public Component Component;
+			[SerializeField]
+			public string Attribute;
+
+			public bool Equals(AttributeBinding other) {
+				return Component.Equals(other.Component) && Attribute.Equals(other.Attribute);
+			}
+			public override bool Equals(object obj) {
+				return obj is AttributeBinding && Equals((AttributeBinding)obj);
+			}
+			public override int GetHashCode() {
+				return Component.GetHashCode() ^ Attribute.GetHashCode();
+			}
+		}
+
+		[SerializeField]
+		StateTweener[] m_children;
+
+		readonly List<string> _statePriority = new List<string>();
+		readonly Dictionary<AttributeBinding, object> _defaults = new Dictionary<AttributeBinding, object>();
+		readonly Dictionary<AttributeBinding, PropertyTweener<object>> _tweeners = new Dictionary<AttributeBinding, PropertyTweener<object>>();
+		readonly Dictionary<string, Dictionary<AttributeBinding, object>> _runtimeStates = new Dictionary<string, Dictionary<AttributeBinding, object>>();
+
+		void Awake() {
+			var types = new Dictionary<AttributeBinding, Type>();
+			foreach (var state in m_states) {
+				Dictionary<AttributeBinding, object> attrs;
+				_statePriority.Add(state.Name);
+				_runtimeStates.Add(state.Name, attrs = new Dictionary<AttributeBinding, object>());
+				foreach (var attr in state.Attributes) {
+					var binding = attr.Attribute;
+					if (!types.TryGetValue(binding, out var type)) {
+						var comp = binding.Component;
+						var ctype = comp.GetType();
+						var path = binding.Attribute.Split('.');
+
+						var propName = path[0];
+						var prop = ctype.GetMember(propName, MemberTypes.Field | MemberTypes.Property, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static).Single();
+						var gvd = FieldLikeHelper.GetGetValueDelegate(prop);
+						var svd = FieldLikeHelper.GetSetValueDelegate(prop);
+
+						Func<object> getter;
+						Action<object> setter;
+						if (path.Length == 1) {
+							type = FieldLikeHelper.GetMemberType(prop);
+							getter = () => gvd(comp);
+							setter = v => svd(comp, v);
+						}
+						else if (path.Length == 2) {
+							var propType = FieldLikeHelper.GetMemberType(prop);
+							var subPropName = path[1];
+							var subProp = propType.GetMember(subPropName, MemberTypes.Field | MemberTypes.Property, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static).Single();
+
+							type = FieldLikeHelper.GetMemberType(subProp);
+							var gsvd = FieldLikeHelper.GetGetValueDelegate(subProp);
+							getter = () => gsvd(gvd(comp));
+							var ssvd = FieldLikeHelper.GetSetValueDelegate(subProp);
+							setter = v => {
+								object obj = gvd(comp);
+								ssvd(obj, v);
+								svd(comp, obj);
+							};
+						}
+						else {
+							throw new FormatException("Invalid attribute path.");
+						}
+						_tweeners.Add(binding, CreateTweener(type, getter, setter));
+						_defaults.Add(binding, getter());
+						types.Add(binding, type);
+					}
+
+					attrs.Add(binding, Convert.ChangeType(attr.Value, type));
+				}
+			}
+			foreach (var def in _defaults) {
+				foreach (var state in _runtimeStates) {
+					if (!state.Value.ContainsKey(def.Key)) {
+						state.Value.Add(def.Key, def.Value);
+					}
+				}
+			}
+			_spcmp = new StatePriorityComparer(this);
+		}
+
+		PropertyTweener<object> CreateTweener(Type type, Func<object> getter, Action<object> setter) {
+			if (type == typeof(byte)) return new PropertyTweener<object>(getter, setter, Tweeners.Byte.Boxed());
+			else if (type == typeof(sbyte)) return new PropertyTweener<object>(getter, setter, Tweeners.SByte.Boxed());
+			else if (type == typeof(short)) return new PropertyTweener<object>(getter, setter, Tweeners.Int16.Boxed());
+			else if (type == typeof(ushort)) return new PropertyTweener<object>(getter, setter, Tweeners.UInt16.Boxed());
+			else if (type == typeof(int)) return new PropertyTweener<object>(getter, setter, Tweeners.Int32.Boxed());
+			else if (type == typeof(uint)) return new PropertyTweener<object>(getter, setter, Tweeners.UInt32.Boxed());
+			else if (type == typeof(long)) return new PropertyTweener<object>(getter, setter, Tweeners.Int64.Boxed());
+			else if (type == typeof(ulong)) return new PropertyTweener<object>(getter, setter, Tweeners.UInt64.Boxed());
+			else if (type == typeof(IntPtr)) return new PropertyTweener<object>(getter, setter, Tweeners.IntPtr.Boxed());
+			else if (type == typeof(UIntPtr)) return new PropertyTweener<object>(getter, setter, Tweeners.UIntPtr.Boxed());
+			else if (type == typeof(float)) return new PropertyTweener<object>(getter, setter, Tweeners.Float.Boxed());
+			else if (type == typeof(double)) return new PropertyTweener<object>(getter, setter, Tweeners.Double.Boxed());
+			else throw new NotSupportedException("Property type not supported.");
+		}
+
+		void Update() {
+			foreach (var tweener in _tweeners) tweener.Value.Advance(Time.deltaTime);
+		}
+
+		readonly List<string> m_cState = new List<string>();
+		public IReadOnlyList<string> CurrentState => m_cState;
+		public void ClearState(float transitionDuration = float.Epsilon) {
+			foreach (var child in m_children) child.ClearState(transitionDuration);
+			m_cState.Clear();
+			foreach (var tweener in _tweeners) {
+				tweener.Value.Start(_defaults[tweener.Key], transitionDuration);
+			}
+		}
+		public void EnterState(string state, float transitionDuration = float.Epsilon) {
+			if (_runtimeStates.TryGetValue(state, out var rs)) {
+				int index = m_cState.BinarySearch(state, _spcmp);
+				if (index < 0) {
+					index = ~index;
+					m_cState.Insert(index, state);
+				}
+				if (index == m_cState.Count - 1) {
+					foreach (var s in rs) {
+						_tweeners[s.Key].Start(s.Value, transitionDuration);
+					}
+				}
+			}
+			foreach (var child in m_children) child.EnterState(state, transitionDuration);
+		}
+		public void ExitState(string state, float transitionDuration = float.Epsilon) {
+			foreach (var child in m_children) child.ExitState(state, transitionDuration);
+			if (!_runtimeStates.ContainsKey(state)) return;
+			int index = m_cState.BinarySearch(state, _spcmp);
+			if (index < 0) return;
+			m_cState.RemoveAt(index);
+			if (index < m_cState.Count) return;
+			var attrs = m_cState.Count == 0 ? _defaults : _runtimeStates[m_cState[m_cState.Count - 1]];
+			foreach (var tweener in _tweeners) {
+				tweener.Value.Start(attrs[tweener.Key], transitionDuration);
+			}
+		}
+
+		StatePriorityComparer _spcmp;
+		class StatePriorityComparer : IComparer<string> {
+			readonly StateTweener _self;
+			public StatePriorityComparer(StateTweener self) {
+				_self = self;
+			}
+			public int Compare(string x, string y) {
+				return _self._statePriority.IndexOf(x).CompareTo(_self._statePriority.IndexOf(y));
+			}
+		}
+	}
+}
diff --git a/Assets/Cryville/Common/Unity/StateTweener.cs.meta b/Assets/Cryville/Common/Unity/StateTweener.cs.meta
new file mode 100644
index 0000000..167abb9
--- /dev/null
+++ b/Assets/Cryville/Common/Unity/StateTweener.cs.meta
@@ -0,0 +1,11 @@
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+guid: d605791cb18d88e4fb0ab6f794361eee
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: