After countless years of FPS experience, I must say Blacklight sits at the top of my list. I consider this the best game ever made and it makes the latest BF and CoD look like childsplay, even graphicswise. Here's why.
Modern day shooters often have limited weapons, you can only fit so many of them into the game before the files gets too large. Not the case with blacklight, there're as many weapons as your imagination allows there to be. And there's always a perfect, and by perfect, I mean perfect perfect, weapon for everyone. Same goes with your playable character, you get to decide exactly how tough and how agile he will be via choosing a variety of armor combinations.
Gameplay, there's so friggin many gamemodes and maps. There's the classical last team standing, search and destroy, capture the flag, team deathmatch, deathmatch, domination, netwar, seige, onslaugh, king of the hill, over a ever growing pool of maps that currently holds 15 , which are Decay, Containment, Vortex, Deadlock, Center, Helodeck, Metro, Seaport, Dropzone, Slumlord, Heavy Metal, Evac, Offshore, Vertigo, Nuken.
Consumer Equilibrium, for those of you who just wants to show off, there're awesome shiny camos and helmet variants you can buy, for those of you who are skilled, blacklight offers everything you need to swag it off to the community, for those of you who'd like to collect and merch stuff, there're nodes and shiny rare collectables you can fuse / trade / sell, and for those that are just starting out on yer FPS career, blacklight provides you with everything you'll ever need to pull yourself up from the bootstraps and be the best possible player ingame.
And best of all, it's free. You don't have to pay a single dime on the game to get just about everything ingame for permenant. If you don't like the game, you can simply delete it out of your computer, no $60 regrets whatsoever.
Do keep in mind that this game was developed in late 2010, and its graphics are still god damn topnotch even compared to all the AAA titles out there today.
You name it, blacklight's got it.
*Edit: Blacklight's no longer dead.