The most 'emotionally-attaching' game for me was HL2. Some people say it was lacking, others say it was great - I'm one of people who thought it was excellent. The story really drew me in, and I actually felt sad when it was over and I was taken away.

I think what did it for me was the first few parts of the game. Stepping off the train and seeing the suppressed life of City 17: the scanners, the civil protection, the general dismal attitude of the place, the raid on the apartment block. It really made me feel that this was a post-apocalyptic world where life was being suppressed and a select few were struggling to fight. From there I was hooked. Then you bring in Dr. Vance, Barney, and Alyx... well call me corny, but that's the most character attachment I've ever had from a game.