Unless you guys are using a certain GML code, do you know how many rooms you’ll have to make 
I mean think about it, If you can grab missile exp. A, but you deside to pass it up and grab missile exp. B first, it gives two or three diffrent rooms. Think of that with 250 missile and over 10 energy tanks.
I guess we’re using a certain GML code.
You can set global variables in Game Maker that retain their values from room to room. Simply deleting any power ups that have already been collected when a room is loaded would work, instead of creating a new room for every possible combination of collected items and whatnot. 
Ha, now that would be one huge game file… Although I can see a problem you guys might have. It looks like you guys make a new room on GM for every “room” in each map on P2D. The map set you guys have planned is huge, so you are going to have over 350 rooms in the game. Won’t that make for an extreamly huge file size?
Every room simply has a bunch of coordinates for tiles. It’s not one big picture.
The rooms are not remade for every event. So missile stuff and other things do not influence the ammount of rooms, it’s all done by code.
I have no idea how many room there would be in the total game. The space frigate is 35 I think.
Last time I counted, there where about 245 room. Give or take a few maybe.