I rather like Blacklight: Retribution (sci-fi FPS). It's similar to the spawn of Battlefield, CoD, and Halo having a bit to much to drink one night after each being dumped and thinking that maybe just this once they, you know, never really saw how much they understood each other, and wouldn't they like to go bare just this once...
Horrible mental imagery aside, the shooty bits are polished to at least a dull glimmer, the meta-game of building guns and loadouts is decently in-depth and stat-fiddly, and while you'll likely get demolished after level 10 when you step into the big boy servers, the F2P model isn't too atrocious.
It's still grabbing fiercely for your wallet, mind. You'll unlock trial items through normal play and leveling, but it's rare to get the really good stuff, and buying things permanently with the in-game currency (equivalent to EXP, more or less) takes a lot of games played to get up enough scratch for any one purchase. Set up, of course, to appeal to our lazier natures (you can buy anything at any time with real money equivalents, and in-game purchases for sweet gear is often level-gated). Also a bit punishing if you take a break, as all the trial gear you've accumulated will have likely poofed when you come back.
But, having dropped roughly 0 Dollars on it myself, I can say that it's pretty great fun.