I think last night ended up being around 6 hours work but maybe half that coding and the other half writing and trying to come up with some kind of idea. Basically, I have the various libraries and stuff together and built to a Hello World sort of state where I probably should've been the night before.
Like I figured in my last post, I'm gonna go for using Undead and Shadows. I'm thinking a basic 2D RTS survival thing with increasing waves of skeletons or some other kind of undead coming towards the player. The player defends himself by shooting shadow orbs at the undead which then upon impact "melts" the undead and leaves its shadow on the ground. If the player later on steps onto one of these shadows he will also melt and the game is over. And of course, if the undead get to the player they kill the player and the game is over. Probably need a life bar in there of some kind but I want to get these various elements in there first.
I'm a ways off of having anything really to show in the ways of screen shots. I'm hoping to at least get the tilemap stuff working and some kind of basic level built tonight. If I can do that then I'll take a shot and working on the sprites a bit so I have something to show off.
Best of luck everyone.
It sounds like you have a pretty solid idea. Hope to see some screens soon!