Specifically PvP? Are you interested in campaigns or co-operative PvE games as well?
I'll just post a fuck huge list anyway.
>Call of Juarez Gunslinger
Short yet amazing, just like my GF:^
>E.Y.E. Divine Cybermancy
It can take a few hours to understand this game. I recommend Mandalore gaming's review. Make a boring and safe character on your first playthrough then try to expiriment on repeat playthroughs.
>Fallout NV
The only good 3d fallout game. Install a fuckload of mods and fixes. It was rushed as hell.
>Stalker franchise
People still debate endlessly about which one is best. If you don't mind the eurojank feel then you should try it.
>Far cry 3 Blooddragon
It's an ubishit game, I liked it anyway
>Insurgency
The least shitty tacticool shooter.
>Metro Franchise
It's on my backlog. I don't have strong opinions on games that I haven't played.
>FEAR
Play the first, avoid the sequels like the plague.
>StarWars Battlefront 2
Back when starwars was good I played this endlessly on the ps2. Servers are back, but you may need to play with some files to make the game run without hiccups.
>Halo
You can find a download on media fire for CE if you're careful and the SVP3 mod gives it a nice overhaul.
Halo 2 can be downloaded from the project cartographer site. The level and enemy design are a bit shitty.
Eldewrito/Halo online is still alive despite Microshit's efforts.