It "works"

It's a buggy mess but it's a working buggy mess

Assets/Prefabs/Portal.prefab

@@ -48,7 +48,6 @@ MonoBehaviour:
   m_OtherPortal: {fileID: 0}
   m_CameraPrefab: {fileID: 1179287573507601862, guid: 1a28b9e152b1d3d419d1881ea498fcbf, type: 3}
   m_PortalRenderer: {fileID: 4162196787169641245}
-  m_PlayerTag: 
   m_PlayerPoint: {fileID: 6158405577604730568}
 --- !u!65 &5568742943214540714
 BoxCollider:
@@ -69,7 +68,7 @@ BoxCollider:
   m_ProvidesContacts: 0
   m_Enabled: 1
   serializedVersion: 3
-  m_Size: {x: 10, y: 10, z: 0.1}
+  m_Size: {x: 10, y: 10, z: 0}
   m_Center: {x: 0, y: 5, z: 0}
 --- !u!1 &2957412639318883996
 GameObject:
@@ -217,5 +216,59 @@ Transform:
   - {fileID: 6525768614182165007}
   - {fileID: 2772991262862259612}
   - {fileID: 6158405577604730568}
+  - {fileID: 8290014685027761188}
   m_Father: {fileID: 0}
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
+--- !u!1 &7967144210440699741
+GameObject:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  serializedVersion: 6
+  m_Component:
+  - component: {fileID: 8290014685027761188}
+  - component: {fileID: 4196137517685965440}
+  m_Layer: 0
+  m_Name: Back
+  m_TagString: Untagged
+  m_Icon: {fileID: 0}
+  m_NavMeshLayer: 0
+  m_StaticEditorFlags: 0
+  m_IsActive: 1
+--- !u!4 &8290014685027761188
+Transform:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 7967144210440699741}
+  serializedVersion: 2
+  m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
+  m_LocalPosition: {x: 0, y: 0, z: 0}
+  m_LocalScale: {x: 1, y: 1, z: 1}
+  m_ConstrainProportionsScale: 0
+  m_Children: []
+  m_Father: {fileID: 3117384245817137028}
+  m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
+--- !u!65 &4196137517685965440
+BoxCollider:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 7967144210440699741}
+  m_Material: {fileID: 0}
+  m_IncludeLayers:
+    serializedVersion: 2
+    m_Bits: 0
+  m_ExcludeLayers:
+    serializedVersion: 2
+    m_Bits: 0
+  m_LayerOverridePriority: 0
+  m_IsTrigger: 0
+  m_ProvidesContacts: 0
+  m_Enabled: 1
+  serializedVersion: 3
+  m_Size: {x: 10, y: 10, z: 5}
+  m_Center: {x: 0, y: 5, z: -3.5}

Assets/Scripts/Player/CameraController.cs

@@ -70,4 +70,7 @@ public class CameraController : MonoBehaviour
         // Sets its location to where it is tracking
         transform.position = m_Tracking.position;
     }
+
+    // Adds a way for external forces to modify the direction the player is looking
+    public void RotatePlayerDirection(Vector2 dif) => m_Rotation += dif;
 }

Assets/Scripts/Player/PlayerFixedUpdate.cs

@@ -22,6 +22,9 @@ public partial class PlayerMovement : MonoBehaviour
     // Fixed Update is called once per physics update
     private void FixedUpdate()
     {
+        // Resets portal state
+        m_PortalFrameCounter = Mathf.Max(0, m_PortalFrameCounter - 1);
+
         // Works out the new state of the player
         UpdatePlayerState();
 
@@ -81,10 +84,21 @@ public partial class PlayerMovement : MonoBehaviour
         m_Body.velocity = v;
 
         // Doubles gravity if falling to feel less floaty
-        if (v.y < 0.0f) { GravityController.Instance().SetScale(8.0f); }
+        if (v.y < 0.0f) { GravityController.Instance().SetScale(2f); }
-        else { GravityController.Instance().SetScale(3f); }
+        else { GravityController.Instance().SetScale(1f); }
 
         // Clears all stored collisions
         m_WallCollisions.Clear();
     }
+
+    public void WentThroughPortal(float change)
+    {
+        // Resets the counter
+        m_PortalFrameCounter = 3;
+
+        // Rotates the velocity of the player
+        Vector3 vel = m_Body.velocity;
+        vel = Quaternion.AngleAxis(change, Vector3.up) * vel;
+        m_Body.velocity = vel;
+    }
 }

Assets/Scripts/Player/PlayerMovement.cs

@@ -82,6 +82,9 @@ public partial class PlayerMovement : MonoBehaviour
     //
     Vector3 m_WallNormal;
 
+    //
+    int m_PortalFrameCounter = 0;
+
     // Only instance of the player
     static PlayerMovement s_Instance;
 
@@ -89,6 +92,8 @@ public partial class PlayerMovement : MonoBehaviour
     public static Vector3 Pos() => s_Instance.transform.position;
     public static void SetPos(Vector3 v) => s_Instance.transform.parent.position = v;
     public static GameObject Object() => s_Instance.gameObject;
+    public static bool CanGoThroughPortals() => s_Instance.m_PortalFrameCounter == 0;
+    public static PlayerMovement Instance() => s_Instance;
 
     // Start is called before the first frame update
     private void Start()

Assets/Scripts/Player/PlayerUpdate.cs

@@ -1,4 +1,5 @@
 using UnityEngine;
+using UnityEngine.SceneManagement;
 
 public partial class PlayerMovement : MonoBehaviour
 {
@@ -56,6 +57,12 @@ public partial class PlayerMovement : MonoBehaviour
         ApplyDrag();
 
         // Displays the speed of the player to the screen
-        m_SpeedDisplay.text = "Speed: " + new Vector3(m_Body.velocity.x, 0.0f, m_Body.velocity.z).magnitude.ToString("0.00") + " m/s";
+        m_SpeedDisplay.text = new Vector3(m_Body.velocity.x, 0.0f, m_Body.velocity.z).magnitude.ToString("0.00") + " m/s";
+
+        // Reloads the game to stop falling off
+        if (Input.GetKey(KeyCode.R))
+        {
+            SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
+        }
     }
 }

Assets/Scripts/Player/SlidingMovement.cs

@@ -36,7 +36,7 @@ public partial class PlayerMovement : MonoBehaviour
             m_Body.AddForce(slopeDir.normalized * m_SlideSpeed * m_Body.mass * 10, ForceMode.Force);
 
             // Checks if the player wants to jump
-            if (m_JumpKeyPressed) { Jump(5.0f, true); }
+            if (m_JumpKeyPressed) { Jump(2.0f, true); }
         }
 
         // If at the start of a slide provides a boost to the player or if the player is on a slope

Assets/Scripts/Player/WallRunningMovement.cs

@@ -39,7 +39,6 @@ public partial class PlayerMovement : MonoBehaviour
 
         else
         {
-            Debug.LogError("SOMETHING WENT WRONG");
             normal = Vector3.zero;
             return false;
         }

Assets/Scripts/Portals/PortalManager.cs

@@ -1,4 +1,3 @@
-using UnityEditor.UIElements;
 using UnityEngine;
 
 public class PortalManager : MonoBehaviour
@@ -54,25 +53,25 @@ public class PortalManager : MonoBehaviour
         // Checks if the player is overlapping with the portal
         if (m_PlayerOverlapping)
         {
+            // Calculates if the player is going towards the portal
             Vector3 difference = PlayerMovement.Pos() - transform.position;
-            float dotProduct = Vector3.Dot(transform.up, difference);
+            float dotProduct = Vector3.Dot(m_PortalRenderer.gameObject.transform.up, difference);
-
-            Debug.Log(dotProduct + "\t" + difference);
 
             // If this is true the player has crossed the portal
-            if (dotProduct < 0f)
+            if (dotProduct < 0f && PlayerMovement.CanGoThroughPortals())
             {
-                Debug.Log("Teleported player");
-
                 // Rotates the player
                 float rotDif = -Quaternion.Angle(transform.rotation, m_OtherManager.transform.rotation);
                 rotDif += 180.0f;
-                PlayerMovement.Orientation().Rotate(Vector3.up, rotDif);
+                CameraController.Instance().RotatePlayerDirection(new Vector2(0f, rotDif));
 
                 // Teleports the player
                 Vector3 offset = Quaternion.Euler(0f, rotDif, 0f) * difference;
                 PlayerMovement.SetPos(m_OtherManager.transform.position + PlayerOffset() - new Vector3(0, 2, 0));
 
+                // Tellss the player it went through a portal
+                PlayerMovement.Instance().WentThroughPortal(rotDif);
+
                 // Stops the overlapping as it has ended
                 m_PlayerOverlapping = false;
             }