#1) Warcraft III (PC)
I have sunk more hours into this game than entire franchises that have been around since before I was born. Hell, I've spent more time clicking units for amusing responses ("Why don't you lead an army instead of touching me?") than playing some other games. And that's excluding all the time I've spent playing custom maps on Battle.net. (The amount of hours I've spent on Battle.net alone is a four-digit number) Playing through the campaign has pretty much been an annual tradition for me for the past eight years.
I love the RPG elements, I love the fleshed out game world, I love about a dozen other things about Warcraft III, but listing them all would might get a bit redundant. (Plus it's 1:30 in the morning and I really need to get my sleep pattern under control) It's not flawless like Super Metroid; off the top of my head, I could name seven things I don't like about it. But if I had to pick one game to play until the coming of the Four Horsemen, it would hardly be a contest.
