one idea i had was a match-3 puzzle game, since i already started one for NES (but haven't finished yet bc i burnt out on trying to work with the PPU, something that wouldn't be a problem in DOS & i get to use a mouse) and there aren't many (to my knowledge) DOS bejeweled clones
i think my first project will be done with Allegro since it makes video and input calls dead simple, but eventually i do want to work with either lighter frameworks or direct hardware access