If they choose a category with lesser participation from the beginning and their app fits in that category, there is no problem.
Emulators would fit in "Fun", right? Emulator vs. Game and Emulator vs. Fart App... hmmmm...

The categories don't need to be set in stone before the 1st April. I guess the developer won't base the decision about which app he wants to code on the available categories.
If you have more questions, just ask!
We'll use a voting process similar to the voting process of the maemo community council election. Very hard to cheat in that system...