This actually concerns me a little as well, though it will take some time before it becomes relvant, but:
I'm making the DoomRL mod for Doom and when (if!) I manage to finish all the levels, including the extra enemies and scripts and stuff, I'd like to make a "graphical" version, that is, Doom with DoomRL-g graphics. The idea is irresistible to me, since it's so utterly pointless and stupid =)
I won't start anytime soon with that, though, since replacing graphics is an easy but slow and boring process, so I'll put it off as much as I can.