A good fan of NIS would probably try to sell you on Disgaea, but honestly, I really do believe it's only for about 1% of the gaming population out there. It's not as crazy hardcore as everyone makes it out to be... unless you want it to be, and then they're underselling the crazy. That said, I really think most people on the Giant Bomb forums should at least try ZHP, which was a generally accessible game and a lot of fun. Again, nuttier than a Snickers, but it worked in that game's favor.
Also, really? Never a Worms game? You only really need to play one (all of them are basic reiterations rather than full-blown sequels), but theyre a lot of fun. Fantastic online community for 'em, too - well, at least when the community is generally active around its release.