LD56 is over. This is the game.

entities/overlay_on_hover.gd

@@ -0,0 +1,8 @@
+extends MeshInstance3D
+
+func _on_mouse_entered() -> void:
+	var overlay_material := preload("res://resources/selectable_overlay.tres") as StandardMaterial3D
+	material_overlay = overlay_material
+
+func _on_mouse_exited() -> void:
+	material_overlay = null