Jam started quite late here so I couldn't get much done yesterday, however I did have time to do some brainstorming and I have decided to make an adventure game with a Space Quest 1-esque text parser where you travel through space, recovering corrupted map data to find your way home.
I've also gotten basic movement working and written a string splitting function as GameMaker doesn't come with one.
It is so annoying that GameMaker doesn't have build in function for splitting strings into arrays.