For the unfamiliar, Dirty Bomb is from the same team that developed the excellent, and maintains some of that game's objective-based gameplay.
It's got a bit of a MOBA vibe to it, with players able to choose from several mercenary characters, each with their own unique weapons and skills. Gameplay-wise, it feels (and looks, actually) a bit like. Except not rubbish.
Currently the servers and accounts are being handled by online gaming service, but the switchover to Steam will cause some brief disruption.
"From the 17th of December, at approximately 2 p.m. PST, until January 2015," writes Splash Damage, "Dirty Bomb will be offline. We’re sorry you won’t be able get your daily fix of mercenary mayhem for a little while, but this method will get the maximum amount of high-quality work and testing done in as short an amount of time as possible. We will return to normal service as quickly as possible, and it’ll soon be time to test the system in the wild once again."
Unfortunately for current players, all beta progress will be wiped upon the transition. Splash Damage says it is "still investigating" as to whether the game will continue to use the existing Nexon account system, or transfer to a new setup. They'll keep players updated in the meantime via email and forum posts.
It's worth checking this out when it comes to Steam. Dirty Bomb's a decent, fun little shooter, and the free-to-play elements seem to be dealt with fairly well.