Bishi Bashi clone would be cool, with 2/3/4 player split screen multiplayer and separately designed games for those.
I know that isn't exactly your cup of tea GH, but imho something "slower", like a logical game a strategy minigame, or a smaller jrp like the 1st Final Fantasy would be awesome for starters - you wouldn't have to struggle with the speed of your game and all that.
Since I discovered FF7 I always dreamed about something like that for the Amiga but never could play it (except that one AMOS game, what's it's name...)
In my mind I designed it... there are 3 main "views/engines" needed: static intro/menu/options/character screens, scrolled in-game zoomed-in view for the locations, interactions and cutscenes, and the big earth-view for travelling - can be static too.
After that's done program in a few hundred items, quest items, main characters, quest characters, monsters and bosses, design a few towns, mazes, etc. ... ... ... piece of cake.