I was referring to Megami Tensei as a whole, not just the flagship. Sorry about that. Yes, the flagship Shin Megami Tensei games are definitely post-apocalyptic with cyberpunk elements (i.e. in SMT II.) I see Soul Hackers as more proverbial cyberpunk ("tech" cyberpunk.)
Persona is more contemporary modern/urban fantasy (though P4 takes place in the inaka- rural countryside.)
Devil Summoner is defintiely alternate history. The Raidou Kuzunoha games are alternate history with specific period settings. Whereas, Devil Summoner and Devil Summoner 2: Soul Hackers are what-if scenarios had the ICBMs in SMT1 been stopped and President Thorman killed.
Oh yeah, I played the demo to this RPGM games a while back and really liked the setting. I think this may be in line with the original poster's FF8 template. http://rpgmaker.net/games/736/
The short demo alone kicks the collective asses of many commercial RPGM games out now, that's for sure.