To play Rocket League on Steam, you need to visit this game's store page and press "Play Game" button. The free weekend is available only until 15 July.
You can also purchase the game at special promotional price.
Starting today, you can play this massively multiplayer online game for FREE!
Play Borderlands Game of the Year Enhanced for free this weekend!
Moonlighter and This War of Mine are going to be the next freebies from Epic Games Store.