hmm
I like HOMM4 better than 2, never played 3, which everyone seems to say is the best.. Bought 5 for 50 bucks, played it for about 10 minutes.. I hate 3d versions of 2d games.. Warcraft 3 kept me busy for about 2 days compared to a month for WC2.. Uhm.. Anyway..
Have you played any of these?
Buck Rogers: Countdown to Doomsday
Buck Rogers: Matrix Cubed
Bad Blood
Bloodnet
I know they are all old DOS games, but they are pretty damn spiffy, and all RPG's.. Bad Blood is a more of an action game, but definitely role playing elements.. And post apocalyptic..
I would suggest something more modern, but nothing has really been released lately that scratches that same itch.. Can't friggin' wait for Borderlands!!