That game generator is great:
"A puzzle game where you wage war on hell because aliens."
Haha that almost describes Disgaea.
On the simple end of the spectrum, I know several people who are always looking for new mini games to add to their social gaming websites. Mostly that kind of thing is clones of tetris, frozen bubble, bejeweled, solitaire (with cards, mahjongg tiles, or pegs/marbles), snake game, asteroids, galaga, missile command, pinball, hangman, shooting gallery (this is based on an amusement park thing not a famous old game). So if you want people to reuse your code, code for these is in consistent demand.
Me, I've got ideas I'd give away but they're all bigger and more complicated. The simpler end of my spectrum would be farming sims and animal breeding sims, tactical combat RPGs, adventure games, and dating sims.