Share your computer?
Now share your games too.
Steam Family Sharing allows close friends and family members to play one another's games while earning their own Steam achievements and saving their own game progress to the Steam cloud. It's all enabled by authorizing a shared computer.
Remember to sign up to beta access by joining the Steam Family Sharing Group.
Family Sharing isn't available for games with some forms of third-party DRM; refer to the The Big List of 3rd Party DRM on Steam for details.