Pickups + Save-diff

scripts/core/SaveState.cs

@@ -0,0 +1,9 @@
+using System.Collections.Generic;
+//using Godot;
+
+public class SaveState
+{
+	public HashSet<string> CollectedPickups { get; set; } = new();
+	//public Vector2I? LastPlayerChunk { get; set; } // optional debug, requires "using Godot;"
+	//public int[]? LastPlayerChunk { get; set; }  // [x,y] same debug as above, does not require Godot
+}