GoldenEye 007 and Perfect Dark are definitely the top two. I spent hundreds of hours on both of those games. When I was in college my friends and I played multiplayer GoldenEye just once. They never wanted to play me again. I love the engine these games are built on.

Halo and Halo 2 are probably the next two most played FPS for me. I played local multiplayer with my college friends a lot on these games.

Goldeneye on the n64 without a doubt.

I can't quite say. It has to be Deus Ex, or UT, or UT2003/4. It could have also been Duke Nukem 3D or Quake 2 (holy shit, thinking about Quake 2 and The Edge, that was so fucking awesome). Honestly, I don't know. I used to play a metric ton of FPS games before they became shit sometime around 2005.

Call of Duty 4 by far, Rainbow Six Vegas is second most probably.

Others I've played a lot are MW2, Black Ops, Halo and No One Lives Forever.

I really don't get why people hate MW2 and Black Ops. FPS isn't my favourite genre but I've spent many hours onto this game. Despite me being crap at MW2. Both PS3 and 360 versions. Although I'm pretty darn good at Black Ops. Also I find 360 owners really hate Black Ops. At around 5:30pm I find only 430k on the 360 and about 615k on the PS3. I guess PS3 owners really love Black Ops.

CoD4

Counter Strike 1.6

Probably either Time Splitters 2 or CS 1.6. It's too hard to say which I played more, TS 2 was over a much shorter period

No offense, but you should redo the math again.  Since 1996 would be be 15-16 years (15 if you count 96 and 11 as 1/2 years, 16, if both are counted as full years).  45,000/15 years = 3,000 hours per year.  3,000/365 days = 8.2 hours per day.

So you are telling me that for the last 15 years, you have averaged 8.2 hours per day, EVERY single day on Goldeneye 64?

Half-life death match.
We played that pretty much every day in lan at the end of the work day. One of us even made a level of the office we worked in. The energy weapon was awesome, you could shoot it at the ground and it would make you fly up into the air to land on the roof of the building. Or you could use it to shoot people through a book case or wall. Laser tripwires were also a favorite to create huge chained booby traps. Stick one on a door or a hatch at the end of a chain to set of the carnage when someone gets close.

The game remembered a lot of the carnage, just after 10 minutes the office was turned into a bloody mess with bullet holes everywhere. There were tons of mods and custom levels. We were running around as anything from homer simpson with a rocket launcher to a giant tube of toothpaste with a crowbar.

It was much more fun to play multiplayer games in the same room, online fps games have never been able to match that.

We also played duke nukem 3D, quake and unreal tournament, but half-life got by far the most time.