Arena-based co-op zombie shooter Killing Floor was updated last night, with four new maps and a Mac 10 machine pistol with incendiary ammo. The game's update philosophy is that the gamey stuff, like weapons and maps, are free to all players. Only new character models, which are a purely aesthetic improvement, cost real money.
The Mac 10 is fun: its damage output is ridiculous for a reasonably priced weapon, but the absurd rate of fire means an empty clip in one second flat. Even if you're flush for ammo, that's a lot of reloading at awkward times. The Firebug class gets a damage bonus with it, can buy it cheaper, and has a chance to set enemies on fire with it. I am now playing Firebug.
This update also reworks the way in-game cash is distributed to players as they mow down zombies: it used to be based solely on kills, so those who finish specimens off were better paid than those who just did a lot of damage. Now it's pro rata, so you get paid proportionally for the damage you did to anything that ultimately dies. It's still not entirely clear where this money comes from or how it arrives in your pockets.
I really like Killing Floor. I think it makes the basic business of redeading the undead more satisfying than Left 4 Dead, and the arena-based structure makes me more willing to replay it than a series of scripted levels. The co-op interactions are pretty much limited to covering and healing, but that's enough for the kind of game it's trying to be.
It's half price on Steam right now - £7.50 in the UK - and it goes into slow motion when you blow something's head off.