The Steam Summer Getaway is a special set that was made available during the 2013 Steam Summer Sale, which ran from 11 July to 22 July 2013. Leading up to and during that time, cards could be earned by crafting badges from any game, or by voting 3 times on Community Choice game sales.
Instead of focusing on a single game like normal Steam trading card sets, this set instead featured 10 cards, each from a different game.