I've got an idea that maybe you could be able to iron out and pull it off.
Most likely everyone here in these forums have played turn-based dungeon crawlers like Nethack, Angband and a hundred alike. And probably you prefer old-school ASCII presentations and not the crappy looking tile-sets that obscure information instead of giving clear display of game.
BUT no one has never done seamless integration between modern 3D game while having ASCII crawler at the background! By seamless I mean that you would have like Grimrock style outlook, but technically could also play with ASCII graphics. The viewpoint could be Diablo-like as ASCII crawlers are directly from up. So in result you would actually have an old-school ASCII crawler represented with brilliant graphics with light and shadows and maybe with real physics. With physics I mean that projectile trajectories would actually be calculated and while deflected they could end up hitting something else, or things that blow could throw things around. Or maybe there could even be gravity based attacks or other nasty tricks.
It could also be possible to add depth to the levels, while this would certainly make it impossible to represent the game in ASCII, since there just isn't practical, clear way to represent Z-coordinate in ASCII games.
My favorite game is a modern crawler, DCSS (http://crawl.develz.org/wordpress/) that has been under active development for several years. Stone Soup has many advanced features and interface options which make the gameplay smooth and compelling for today's standards. Maybe this could be used as an 'background' and create 3D environment around it.
So, what do you think? Just wrap it up and on the shelves, we are getting ready to aim our mouses at 'buy'
