Dirty Bomb, the “free-to-win” first-person shooter from Splash Damage, has officially launched its Open Beta, now available to users on Steam in North America, Europe, Australia/New Zealand and Brazil.

12 Mercs are available to start, two of which — Skyhammer and Aura — will always be available for free to everyone. A rotating assortment of additional Mercs will also be available for free on an ongoing basis. Here are the first three Mercs you’ll be able to get your hands on right away:

• Kira – “a powerful tactical character who can rain down hell from above with her Orbital Laser Strike, perfect for clearing out defenses and campers”
• Sawbonez – “a frontline support medic equipped with a Submachine Gun and Defibrillator Paddles, who is highly effective at reviving his teammates to full health”
• Fragger – “an aggressive pointman and straight-up player-slayer, with a big gun, lots of ammo, and devastating Frag grenades”

Other Mercs like the long-range sniper Vassili and the Minigun-wielding tank, Rhino, can be purchased with Credits or through the Steam Wallet.

The Open Beta offers five maps and two modes, but Splash Damage plans to add more over the course of the coming months, some in finished form and others in prototype phases.

You can play Dirty Bomb for free by visiting the game’s official Steam page.