If you ignore this warning and proceed anyway:

Several third-party websites offer Counter-Strike: Source for download without Steam. These websites host the game's installation files, which can be downloaded and installed on your computer. However, be cautious when using third-party websites, as they may bundle the game with malware or other unwanted software.

: The official version includes cloud saves, achievements, and access to thousands of verified community servers. Installation : Download the Steam Client . Create a free account.