The multiplayer shooter/RTS hybrid Nuclear Dawn is going to be free to play this weekend on Steam. Its inventive map design, diverse classes and a smart commander mode impressed us in our Nuclear Dawn review, and you'll get double experience for playing for free. It'll be on sale all weekend at 40% off, and if you buy before Sunday you'll get an exclusive P-900 sidearm (in the game). Free guns! Free shooting of guns! What's not to like?