It's tough to pinpoint the exact game that kick started the free-to-play craze, but you can certainly make the argument that Gun Bros was largely responsible. Released in October 2010, Glu Mobile's freemium shooter offered players a lengthy campaign to spend blasting baddies, along with in-app purchases in case they needed to go the easy route.
Now comes word that Glu has a sequel, aptly titled Gun Bros 2, set to launch on iOS and Android. No big details yet, but the debut trailer provides a solid look at the characters. That said, we'll have plenty more on this title in the weeks ahead.