I didn't really consider putting secret items in the game.. thanks for the reminder ;)
Now that you mention it, I gotta work out what the items are going to look like. The boss rewards are keys.. I think I'll just have secret items as weapons, like in iwbtg, but put some easter egg graphic or something in the rooms where you find them.
@DimJim: You can't get past the Doom thing.. for some reason when I compiled it with GM7 the collisions changed or something, and the boss hits you when he spins from right to left when he's not supposed to. The bug is fixed, and the boss will be fully playable in the next demo (which will contain all 3 bosses so far, and perhaps the beginning of the path to another one)
I'm going to have an underwater section, where the player will be able to double jump all the time.
Not entirely sure why my saving system is bugging out, but oh well. The main bug is where you sometimes get caught in walls when jumping up or falling down from one room to the next, I know what causes this, and may have a fix for it in the next release.