The excellent Command & Conquer: Red Alert 2 is the latest game to be offered for free via Origin'sinitiative.
You can grab the original game released back in 2000, a brilliant RTS packed with some of the absolute best (by which I mean they are utterly terrible) live-action cutscenes in video game history, as well as expansion
This isn't a free weekend style deal, remember. As long as you grab the game before the offer runs out, it will be permanently added to your Origin library. If you've never enjoyed the simple thrill of unleashing waves of Kirov airships upon an unsuspecting enemy, I suggest you give it a go.