diff --git a/Graph/DirectedGraph.cs b/Graph/DirectedGraph.cs
index 70c2cde..2ebcd5c 100644
--- a/Graph/DirectedGraph.cs
+++ b/Graph/DirectedGraph.cs
@@ -10,7 +10,7 @@ namespace MoonTools.Core.Graph
         finish
     }
 
-    public class DirectedGraph<TNode, TEdgeData> : IGraph<TNode, TEdgeData>
+    public class DirectedGraph<TNode, TEdgeData> : IGraph<TNode, TEdgeData> where TNode : IEquatable<TNode>
     {
         protected HashSet<TNode> nodes = new HashSet<TNode>();
         protected HashSet<(TNode, TNode)> edges = new HashSet<(TNode, TNode)>();
diff --git a/Graph/DirectedWeightedMultiGraph.cs b/Graph/DirectedWeightedMultiGraph.cs
new file mode 100644
index 0000000..839ccee
--- /dev/null
+++ b/Graph/DirectedWeightedMultiGraph.cs
@@ -0,0 +1,195 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using MoreLinq;
+
+namespace MoonTools.Core.Graph
+{
+    public class DirectedWeightedMultiGraph<TNode, TEdgeData> : IGraph<TNode, TEdgeData> where TNode : IEquatable<TNode>
+    {
+        protected HashSet<TNode> nodes = new HashSet<TNode>();
+        protected Dictionary<TNode, HashSet<TNode>> neighbors = new Dictionary<TNode, HashSet<TNode>>();
+        protected Dictionary<(TNode, TNode), HashSet<Guid>> edges = new Dictionary<(TNode, TNode), HashSet<Guid>>();
+        protected Dictionary<Guid, (TNode, TNode)> IDToEdge = new Dictionary<Guid, (TNode, TNode)>();
+        protected Dictionary<Guid, int> weights = new Dictionary<Guid, int>();
+        protected Dictionary<Guid, TEdgeData> edgeToEdgeData = new Dictionary<Guid, TEdgeData>();
+
+        // store search sets to prevent GC
+        protected HashSet<TNode> openSet = new HashSet<TNode>();
+        protected HashSet<TNode> closedSet = new HashSet<TNode>();
+        protected Dictionary<TNode, int> gScore = new Dictionary<TNode, int>();
+        protected Dictionary<TNode, int> fScore = new Dictionary<TNode, int>();
+        protected Dictionary<TNode, Guid> cameFrom = new Dictionary<TNode, Guid>();
+
+        public IEnumerable<TNode> Nodes => nodes;
+
+        public void AddNode(TNode node)
+        {
+            nodes.Add(node);
+        }
+
+        public void AddNodes(params TNode[] nodes)
+        {
+            foreach (var node in nodes)
+            {
+                AddNode(node);
+            }
+        }
+
+        public void AddEdge(TNode v, TNode u, int weight, TEdgeData data)
+        {
+            if (Exists(v) && Exists(u))
+            {
+                var id = Guid.NewGuid();
+                if (!neighbors.ContainsKey(v))
+                {
+                    neighbors[v] = new HashSet<TNode>();
+                }
+                neighbors[v].Add(u);
+                weights.Add(id, weight);
+                if (!edges.ContainsKey((v, u)))
+                {
+                    edges[(v, u)] = new HashSet<Guid>();
+                }
+                edges[(v, u)].Add(id);
+                edgeToEdgeData.Add(id, data);
+                IDToEdge.Add(id, (v, u));
+            }
+            else if (!Exists(v))
+            {
+                throw new InvalidVertexException("Vertex {0} does not exist in the graph", v);
+            }
+            else
+            {
+                throw new InvalidVertexException("Vertex {0} does not exist in the graph", u);
+            }
+        }
+
+        public void AddEdges(params (TNode, TNode, int, TEdgeData)[] edges)
+        {
+            foreach (var edge in edges)
+            {
+                AddEdge(edge.Item1, edge.Item2, edge.Item3, edge.Item4);
+            }
+        }
+
+        public void Clear()
+        {
+            nodes.Clear();
+            neighbors.Clear();
+            weights.Clear();
+            edgeToEdgeData.Clear();
+        }
+
+        private void CheckNodes(params TNode[] givenNodes)
+        {
+            foreach (var node in givenNodes)
+            {
+                if (!Exists(node))
+                {
+                    throw new ArgumentException($"Vertex {node} does not exist in the graph");
+                }
+            }
+        }
+
+        public IEnumerable<Guid> EdgeIDs(TNode v, TNode u)
+        {
+            CheckNodes(v, u);
+            return edges.ContainsKey((v, u)) ? edges[(v, u)] : Enumerable.Empty<Guid>();
+        }
+
+        public bool Exists(TNode node)
+        {
+            return nodes.Contains(node);
+        }
+
+        public bool Exists(TNode v, TNode u)
+        {
+            CheckNodes(v, u);
+            return edges.ContainsKey((v, u));
+        }
+
+        public IEnumerable<TNode> Neighbors(TNode node)
+        {
+            CheckNodes(node);
+            return neighbors.ContainsKey(node) ? neighbors[node] : Enumerable.Empty<TNode>();
+        }
+
+        public IEnumerable<int> Weights(TNode v, TNode u)
+        {
+            CheckNodes(v, u);
+            return edges[(v, u)].Select(id => weights[id]);
+        }
+
+        public TEdgeData EdgeData(Guid id)
+        {
+            if (!edgeToEdgeData.ContainsKey(id))
+            {
+                throw new ArgumentException($"Edge {id} does not exist in the graph.");
+            }
+
+            return edgeToEdgeData[id];
+        }
+
+        private IEnumerable<Guid> ReconstructPath(Dictionary<TNode, Guid> cameFrom, TNode currentNode)
+        {
+            while (cameFrom.ContainsKey(currentNode))
+            {
+                var edgeID = cameFrom[currentNode];
+                var edge = IDToEdge[edgeID];
+                currentNode = edge.Item1;
+                yield return edgeID;
+            }
+        }
+
+        public IEnumerable<Guid> AStarShortestPath(TNode start, TNode end, Func<TNode, TNode, int> heuristic)
+        {
+            CheckNodes(start, end);
+
+            openSet.Clear();
+            closedSet.Clear();
+            gScore.Clear();
+            fScore.Clear();
+            cameFrom.Clear();
+
+            openSet.Add(start);
+
+            gScore[start] = 0;
+            fScore[start] = heuristic(start, end);
+
+            while (openSet.Any())
+            {
+                var currentNode = openSet.MinBy(node => fScore[node]).First();
+
+                if (currentNode.Equals(end))
+                {
+                    return ReconstructPath(cameFrom, currentNode).Reverse();
+                }
+
+                openSet.Remove(currentNode);
+                closedSet.Add(currentNode);
+
+                foreach (var neighbor in Neighbors(currentNode))
+                {
+                    if (!closedSet.Contains(neighbor))
+                    {
+                        var lowestEdgeID = EdgeIDs(currentNode, neighbor).MinBy(id => weights[id]).First();
+                        var weight = weights[lowestEdgeID];
+
+                        var tentativeGScore = gScore.ContainsKey(currentNode) ? gScore[currentNode] + weight : int.MaxValue;
+
+                        if (!openSet.Contains(neighbor) || tentativeGScore < gScore[neighbor])
+                        {
+                            cameFrom[neighbor] = lowestEdgeID;
+                            gScore[neighbor] = tentativeGScore;
+                            fScore[neighbor] = tentativeGScore + heuristic(neighbor, end);
+                            openSet.Add(neighbor);
+                        }
+                    }
+                }
+            }
+
+            return Enumerable.Empty<Guid>();
+        }
+    }
+}
\ No newline at end of file
diff --git a/Graph/IGraph.cs b/Graph/IGraph.cs
index 1fe0be6..a3939f1 100644
--- a/Graph/IGraph.cs
+++ b/Graph/IGraph.cs
@@ -2,7 +2,7 @@ using System.Collections.Generic;
 
 namespace MoonTools.Core.Graph
 {
-    public interface IGraph<TNode, TEdgeData>
+    public interface IGraph<TNode, TEdgeData> where TNode : System.IEquatable<TNode>
     {
         IEnumerable<TNode> Nodes { get; }
 
diff --git a/Graph/MoonTools.Core.Graph.csproj b/Graph/MoonTools.Core.Graph.csproj
index 72764a6..e69a172 100644
--- a/Graph/MoonTools.Core.Graph.csproj
+++ b/Graph/MoonTools.Core.Graph.csproj
@@ -1,7 +1,8 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
-  </PropertyGroup>
-
-</Project>
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="morelinq" Version="3.2.0"/>
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/Graph/UndirectedGraph.cs b/Graph/UndirectedGraph.cs
deleted file mode 100644
index d64e306..0000000
--- a/Graph/UndirectedGraph.cs
+++ /dev/null
@@ -1,7 +0,0 @@
-namespace MoonTools.Core.Graph
-{
-    public class UndirectedGraph<T>
-    {
-
-    }
-}
\ No newline at end of file
diff --git a/test/DirectedGraphTest.cs b/test/DirectedGraphTest.cs
index 4481c1e..106ae08 100644
--- a/test/DirectedGraphTest.cs
+++ b/test/DirectedGraphTest.cs
@@ -8,8 +8,6 @@ using MoonTools.Core.Graph;
 
 namespace Tests
 {
-    struct EdgeData { }
-
     public class DirectedGraphTest
     {
         EdgeData dummyEdgeData;
@@ -399,17 +397,12 @@ namespace Tests
             myGraph.Exists((1, 2)).Should().BeTrue();
         }
 
-        struct TestEdgeData
-        {
-            public int testNum;
-        }
-
         [Test]
         public void EdgeData()
         {
-            var myGraph = new DirectedGraph<int, TestEdgeData>();
+            var myGraph = new DirectedGraph<int, NumEdgeData>();
             myGraph.AddNodes(1, 2);
-            myGraph.AddEdge(1, 2, new TestEdgeData { testNum = 4 });
+            myGraph.AddEdge(1, 2, new NumEdgeData { testNum = 4 });
 
             myGraph.EdgeData((1, 2)).testNum.Should().Be(4);
         }
diff --git a/test/DirectedWeightedMultiGraph.cs b/test/DirectedWeightedMultiGraph.cs
new file mode 100644
index 0000000..abdf254
--- /dev/null
+++ b/test/DirectedWeightedMultiGraph.cs
@@ -0,0 +1,252 @@
+using NUnit.Framework;
+using FluentAssertions;
+
+using MoonTools.Core.Graph;
+using System.Linq;
+
+namespace Tests
+{
+    public class DirectedWeightedMultiGraphTests
+    {
+        EdgeData dummyEdgeData;
+
+        [Test]
+        public void AddNode()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNode(4);
+
+            Assert.That(myGraph.Nodes, Does.Contain(4));
+        }
+
+        [Test]
+        public void AddNodes()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNodes(4, 20, 69);
+
+            myGraph.Exists(4).Should().BeTrue();
+            myGraph.Exists(20).Should().BeTrue();
+            myGraph.Exists(69).Should().BeTrue();
+        }
+
+        [Test]
+        public void AddEdge()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNodes(5, 6);
+            myGraph.AddEdge(5, 6, 10, dummyEdgeData);
+
+            myGraph.Neighbors(5).Should().Contain(6);
+        }
+
+        [Test]
+        public void AddEdges()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNodes(1, 2, 3, 4);
+            myGraph.AddEdges(
+                (1, 2, 5, dummyEdgeData),
+                (2, 3, 6, dummyEdgeData),
+                (2, 4, 7, dummyEdgeData),
+                (3, 4, 8, dummyEdgeData)
+            );
+
+            myGraph.Neighbors(1).Should().Contain(2);
+            myGraph.Neighbors(2).Should().Contain(3);
+            myGraph.Neighbors(2).Should().Contain(4);
+            myGraph.Neighbors(3).Should().Contain(4);
+            myGraph.Neighbors(1).Should().NotContain(4);
+
+            myGraph.EdgeIDs(1, 2).Should().HaveCount(1);
+            myGraph.Weights(1, 2).Should().Contain(5);
+        }
+
+        [Test]
+        public void AddMultiEdges()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNodes(1, 2, 3, 4);
+            myGraph.AddEdges(
+                (1, 2, 5, dummyEdgeData),
+                (2, 3, 6, dummyEdgeData),
+                (2, 4, 7, dummyEdgeData),
+                (2, 4, 8, dummyEdgeData)
+            );
+
+            myGraph.Neighbors(1).Should().Contain(2);
+            myGraph.Neighbors(2).Should().Contain(3);
+            myGraph.Neighbors(2).Should().Contain(4);
+            myGraph.Neighbors(1).Should().NotContain(4);
+
+            myGraph.EdgeIDs(2, 4).Should().HaveCount(2);
+            myGraph.Weights(2, 4).Should().HaveCount(2);
+            myGraph.Weights(2, 4).Should().Contain(7);
+            myGraph.Weights(2, 4).Should().Contain(8);
+        }
+
+        [Test]
+        public void Clear()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNodes(1, 2, 3, 4);
+            myGraph.AddEdges(
+                (1, 2, 5, dummyEdgeData),
+                (2, 3, 6, dummyEdgeData),
+                (2, 4, 7, dummyEdgeData),
+                (2, 4, 8, dummyEdgeData)
+            );
+
+            myGraph.Clear();
+
+            myGraph.Invoking(x => x.Neighbors(1)).Should().Throw<System.ArgumentException>();
+            myGraph.Invoking(x => x.Weights(1, 2)).Should().Throw<System.ArgumentException>();
+            myGraph.Invoking(x => x.EdgeIDs(1, 2)).Should().Throw<System.ArgumentException>();
+        }
+
+        [Test]
+        public void Edges()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNodes(1, 2, 3);
+            myGraph.AddEdges(
+                (1, 2, 4, dummyEdgeData),
+                (1, 2, 3, dummyEdgeData),
+                (2, 3, 5, dummyEdgeData)
+            );
+
+            myGraph.EdgeIDs(1, 2).Should().HaveCount(2);
+            myGraph.EdgeIDs(2, 3).Should().HaveCount(1);
+        }
+
+        [Test]
+        public void NodeExists()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNodes(1, 2, 3);
+            myGraph.AddEdges(
+                (1, 2, 4, dummyEdgeData),
+                (1, 2, 3, dummyEdgeData),
+                (2, 3, 5, dummyEdgeData)
+            );
+
+            myGraph.Exists(1).Should().BeTrue();
+            myGraph.Exists(2).Should().BeTrue();
+            myGraph.Exists(3).Should().BeTrue();
+            myGraph.Exists(4).Should().BeFalse();
+        }
+
+        [Test]
+        public void EdgeExists()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNodes(1, 2, 3);
+            myGraph.AddEdges(
+                (1, 2, 4, dummyEdgeData),
+                (1, 2, 3, dummyEdgeData),
+                (2, 3, 5, dummyEdgeData)
+            );
+
+            myGraph.Exists(1, 2).Should().BeTrue();
+            myGraph.Exists(2, 3).Should().BeTrue();
+            myGraph.Exists(1, 3).Should().BeFalse();
+            myGraph.Invoking(x => x.Exists(3, 4)).Should().Throw<System.ArgumentException>();
+        }
+
+        [Test]
+        public void Neighbors()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNodes(1, 2, 3);
+            myGraph.AddEdges(
+                (1, 2, 4, dummyEdgeData),
+                (1, 2, 3, dummyEdgeData),
+                (2, 3, 5, dummyEdgeData)
+            );
+
+            myGraph.Neighbors(1).Should().Contain(2);
+            myGraph.Neighbors(2).Should().Contain(3);
+            myGraph.Neighbors(1).Should().NotContain(3);
+            myGraph.Invoking(x => x.Neighbors(4)).Should().Throw<System.ArgumentException>();
+        }
+
+        [Test]
+        public void Weights()
+        {
+            var myGraph = new DirectedWeightedMultiGraph<int, EdgeData>();
+            myGraph.AddNodes(1, 2, 3);
+            myGraph.AddEdges(
+                (1, 2, 4, dummyEdgeData),
+                (1, 2, 3, dummyEdgeData),
+                (2, 3, 5, dummyEdgeData)
+            );
+
+            myGraph.Weights(1, 2).Should().Contain(3);
+            myGraph.Weights(1, 2).Should().Contain(4);
+            myGraph.Weights(2, 3).Should().Contain(5);
+            myGraph.Invoking(x => x.Weights(3, 4)).Should().Throw<System.ArgumentException>();
+        }
+
+        [Test]
+        public void EdgeData()
+        {
+            var a = new NumEdgeData { testNum = 3 };
+            var b = new NumEdgeData { testNum = 4 };
+            var c = new NumEdgeData { testNum = 5 };
+
+            var myGraph = new DirectedWeightedMultiGraph<int, NumEdgeData>();
+            myGraph.AddNodes(1, 2, 3);
+            myGraph.AddEdges(
+                (1, 2, 4, a),
+                (1, 2, 3, b),
+                (2, 3, 5, c)
+            );
+
+            myGraph.EdgeIDs(1, 2).Select(id => myGraph.EdgeData(id)).Should().Contain(a);
+            myGraph.EdgeIDs(1, 2).Select(id => myGraph.EdgeData(id)).Should().Contain(b);
+            myGraph.EdgeIDs(2, 3).Select(id => myGraph.EdgeData(id)).Should().Contain(c);
+            myGraph.Invoking(x => x.EdgeData(new System.Guid())).Should().Throw<System.ArgumentException>();
+        }
+
+        [Test]
+        public void AStarShortestPath()
+        {
+            var run = new MoveTypeEdgeData { moveType = MoveType.Run };
+            var jump = new MoveTypeEdgeData { moveType = MoveType.Jump };
+            var wallJump = new MoveTypeEdgeData { moveType = MoveType.WallJump };
+
+            var myGraph = new DirectedWeightedMultiGraph<char, MoveTypeEdgeData>();
+            myGraph.AddNodes('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h');
+            myGraph.AddEdges(
+                ('a', 'b', 2, run),
+                ('a', 'c', 1, jump),
+                ('a', 'c', 3, run),
+                ('a', 'e', 4, wallJump),
+                ('b', 'd', 2, jump),
+                ('b', 'd', 5, run),
+                ('b', 'e', 1, run),
+                ('c', 'g', 2, run),
+                ('c', 'g', 4, jump),
+                ('c', 'h', 11, run),
+                ('d', 'c', 3, jump),
+                ('d', 'f', 2, run),
+                ('d', 'h', 3, wallJump),
+                ('e', 'f', 5, run),
+                ('f', 'd', 2, run),
+                ('f', 'h', 6, wallJump),
+                ('g', 'h', 7, run),
+                ('h', 'f', 1, jump)
+            );
+
+            myGraph
+                .AStarShortestPath('a', 'h', (x, y) => 15)
+                .Select(id => myGraph.EdgeData(id))
+                .Should()
+                .ContainInOrder(
+                    run, jump, wallJump
+                )
+                .And
+                .HaveCount(3);
+        }
+    }
+}
\ No newline at end of file
diff --git a/test/Structs.cs b/test/Structs.cs
new file mode 100644
index 0000000..9afa939
--- /dev/null
+++ b/test/Structs.cs
@@ -0,0 +1,18 @@
+namespace Tests
+{
+    public enum MoveType
+    {
+        Run,
+        Jump,
+        WallJump
+    }
+    public struct EdgeData { }
+    public struct NumEdgeData
+    {
+        public int testNum;
+    }
+    public struct MoveTypeEdgeData
+    {
+        public MoveType moveType;
+    }
+}
\ No newline at end of file