Games sold on Bundle Stars are redeemed on Steam. We don't delivery physical, boxed product instead provide you with "keys" (sequences of letters and numbers) unique to you which you redeem (enter) in Steam to gain access to the game so you can download it and run it on your PC.
Most games are available for Windows, some are available for Mac OSX and/or Linux - it is important to check the "System Requirements" for each game before buying to ensure the computer and operating system you use is supported.
Steam is a free piece of software that allows you to manage your games, buy new ones, and interact with the Steam community.
Steam is downloaded from www.steampowered.com
For more information on installing and using Steam, please refer to this article.