A trio of free weekend trials on Steam mean that all and sundry can enjoy what are, as I understand, three figures and ideals important to PC gaming: soldiers, vampires, and jetplanes. They all, naturally, do fighting. Not each other, mind–others of their kind. None of these games will let you e.g. pilot a fighter jet battling winged vampires. More’s the pity, really.
Multiplayer futureplane game Strike Vector and realish FPS Insurgency have respectable sales to accompany their free weekend trials, and technically human vs. vamp arenakiller Nosgoth does too but that’ll be free-to-play at launch so it’s less special.