Neverwinter nights is a brilliant game because of the mod-friendliness. Who cares about the original official campaign? There are so many mods out now it's hard to make time for the good ones, and if you include every single one I think you could be playing for years(in suffering, because there's lots of crap out there. But that's not the point! <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />) It's just amazing to watch the community grow better and better as time goes on.

If you try any mods I recommend looking at the newer ones. My personal favorite is Rick Burton's paladin trilogy(not completely finished yet) which can be found at: http://nwvault.ign.com

Anyway, here's my list:

1.Neverwinter nights
2.Planescape torment
3.Diablo 2
4.Final Fantasy 8(Deserves to be mentioned.)
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5.Beyond divinity(Sorry, larian! Others have given lots of reasons why.)