Steam offers the Counter-Strike: Global Offensive Operation Payback Pass for Windows or Mac for 99 cents. (Click the "Buy a pass..." banner to launch Steam and purchase it.) That's $5 off and the best price we've seen for this pass, which grants you access to seven community-created multiplayer game maps. Note that the dedicated servers for these maps will only be up until July 31. (You'll need to already own CS: GO to use them.) Deal ends June 17.