>>159
If you go that way, Starcraft and Half-Life (+ numerous mods) were probably the most long lasting... but War3 is probably headed that way, I guess.

I think one of the last REALLY GOOD games I've played has been Mass Effect. The game itself had many flaws, notably some weaker side quests and relatively short lifespan, but the universe was so credible (honestly, it's the greatest Space Opera setting I've seen in quite a while) and the dialogue so well written... I got all the way into it. Can't wait for the sequels.