Samsung's giving away Modern Combat 3 to Galaxy S II owners for free today, but there's a catch — you can only get it from the Samsung Apps store. The game, which just launched on Android in December alongside Frontline Commando, normally costs $6.99 on both Android and iOS. And while it's free for all Galaxy II S owners, it remains full price in the Android Market. Just make sure to clear some space on your phone, as Modern Combat 3 is a 1GB+ download.