Two months ago I came up with a game design which required a theme. After all this time of wrestling with how the mechanic would work, and what graphics set would be used, I've decided that all this time I've been barking up the wrong tree.
So "Bob" Goes to Dobbstown will be a semi-puzzle tile-pushing game like the LID I made way back in the 1990s. The stage will still be 640x480px, but I'm currently looking at doing up the graphics a bit which may involve changing the tile size to something more visible. When I wrote the original LID in C++ with the SDL library the game was played fullscreen. Not too big on modern displays though.
Once I've got a basic LID, I can start throwing extras into the mix - maybe enemies that ruin your carefully planned groupings, or static ones that you need to make groups with the tiles beneath them to get rid of, and of course powerups. Everyone likes powerups.