[FREE] Airscape, Saviors and Spaceport Hope

This one is a bit different. You have to install a Chrome plugin (and can uninstall it directly after you got the games).

http://super-steam.net/

• Install the browser plugin
• Go to your steam profile page
• Refresh if necessary
• You get 3 steam keys, which seem to always be the 3 mentioned games.

I believe all 3 games have cards (too lazy to check ^^).