I just finished To The Moon and I loooved it and I cried... Planescape: Torment, The Longest Journey and Sanitarium are other games that I loved with great writing, a good atmosphere and some emotional moments.

And now, I'm looking for another game, any suggestion? Thank you!

Still Life

Bastion
Sequence
Enslaved: Odyssey to the West
Majin and the Forsaken Kingdom (though I've yet to every hear from anyone else who's actually played this how they liked it)

Arguably Defense Grid has some pretty outstanding story given that it's tower defense.

Syberia

To the Moon was incredible, but it's one of those games that is so indie and low budget that it probably won't ever get much attention, sadly. But if you want some great games, I know of a bunch--though most are for the current gen of consoles or slightly higher pc requirements, if that's ok?

I'd like to add Machinarium, just for fun, because there's not script. It's well written though.

The replies are fast ! Thank you for your suggestions ! Yeah, that's okay :)

Legacy of Kain: Blood Omen and the other games in the series.

Outstanding writing. Novel quality.

Okay, well I have no idea what kind of games you know about or like but here's some of my favorites with great writing/dialogue/story.

Bioshock-- this is a no brainer. Probably the best shooter of the generation.

Bioshock 2-- maybe even better than the first, so forget that last comment lol.

Portal/Portal 2--The funniest games you'll probably ever play.

Red Dead Redemption--console exclusive, but it's probably Rockstar's best and most mature title.

Alan Wake--some may debate me on this, but I thought the writing and story were excellent.

Deadly Premonition--I'm not really sure whether or not you'd call this great writing or dialogue, but it has one of the weirdest and most original casts and stories you'll ever play. A 360 exclusive, and it looks like crap, but give it a try if you can. Read about it on Gamesradar to get a very favorable viewpoint.

Uncharted-- the series as a whole has great writing and voice acting, but personally I didn't like the gameplay much.

I just bought it on here, but people seem to think very highly of Arcanum and Divine Divinity. I only just started them, so you'll have to check them out yourself.

+1

I played Bastion, Portal 1 - 2, Machinarium and Syberia. They were all great and I will look for the other recommendations :)

I found the original campaigns of HoMM4 quite well written, but the expansions are awful......

I liked Dear Esther.

Planescape: Torment. This one's a no-brainer.

Deus Ex: Though the story is quite predictable (if after the first couple of missions, you still haven't figured out that the NSF will turn out to be the good guys in a few more missions, you're officially brain dead), there is a lot of effort put into building it up and creating the feel of a world larger than the immediate environments.

Golden Sun 1 + 2. A JRPG that actually has a story that isn't a pretentious wank with whiny, angst-ridden characters. Other than that, the first game is pretty standard "save the world from the baddies" fare, but it gets quite interesting and somewhat unpredictable in the second game.

Zork: Grand Inquisitor. Maybe it's just the nostalgia talking, but I've played through it countless times and it still makes me laugh every time.

I'm waiting for the commercial game coming this Valentine :P