It's an interesting idea, but unfortunately, I keep getting the same crash returning to the grapple room after the 'first' coin so I can't progress very far:
-
FATAL ERROR in
action number 1
of Step Event0
for object obj_player:
Unable to find any instance for object index '100393' name '<undefined>'
called from - gml_Object_obj_player_Step_0 (line 99)
-
I think it's triggered when I try to grapple on to the ceiling in that room, but I'm not sure.