Did you know that Hothead Games just released a free-to-play action game called Rivals at War? Well, they did. And now you know about it!
Rivals at War combines Rainbow Six/X-COM styly gameplay, where you put together your own squad of commandos through a trading card style interface. Once your team is assembled, you can send them into battle against other real-world players and monitor the results.
Since this is a freemium game, you do this by buying cards through the in-game store with coins. Naturally, you can either earn these coins (slowly), or purchase them (fast), and go from there. The cards let you recruit new units, unlock weapons, and use power-ups like accuracy.