I, for some strange coincidence, had the pleasure of playing 999 and Ghost Trick at the same time. Both mindblowing games with mindblowing conclussions. So since OP recommended 999, I strongly suggest giving Ghost Trick a chance.
The Dead Rising series. Especially if you love zombies, wacky-but-dark humour, some touches of drama, silliness and gore. This series is so incredible fun. Minus Dead Rising 3, that one is a bit disappointing in comparison to the other two (Still great, though!)
Serious Sam. Awesome "modern" FPS with every ounce of old-school spirit.
Trauma Center games are interesting. They not only offer a challenging but fun gameplay, but also goes their way to introduce the player to a mythological plot full of twists and things. Check it out!
Max Payne trilogy, because yes. Nothing like noir drama with the ability to make time go slower.
