Cool game, the lighting effects are great. I would like to see levels that are a bit less linear and that make use of being able to deactivate the switches, though I understand that you were working under strict time constraints. I end up scrapping ideas and starting over quite often during jams, so I usually start with something like art or basic movement code that I can reuse pieces of in case I need to switch projects.
Also, just out of curiosity, is there a specific reason for using GameMaker 7 (I am assuming that it was used based on the loading bar) rather than one of the newer iterations? There's nothing wrong with it (I am actually quite fond of 7, as it was the first engine I used), though it is definitely rare to see nowadays.