We're making a game for our Java course and we're thinking of making something like Flash Flash Revolution, only in Java. Is this anywhere near possible? Or should we just make a tile-based game like Spyhunter...?

I'd really appreciate some help or comments. ^^

I should be possible in Java. It looks like a pretty simple game from the screenshots I saw.
All the games on this page are written in Java with LWJGL to give you an idea of what can be done.

Dance Dance Revolution emulator eh...
Well, I know there are some C++ implementations out there, might even be open source, but at least they have this nice little thing called scripts, so you don't have to make your own step files...
Check out www.stepmania.com
It uses sprites for everything, so you could even steal the graphics (a lot of free graphics there, as fans make their own stuff and upload it)...
Just head on over to one of the theme sites...

The one thing you should ask yourself isn't if it's possible, but whether you have time or not...
Making a tile-based game takes a lot of time too though, so the issue here is making sure timing is correct, and that you pick-up keyboard and/or dance-pad events quickly enough, so they get correct timing according to what's on the screen, but it should work using LWJGL really...