If you’re looking to play the real game, the best (and safest) way is to grab it on Steam, where it frequently goes on sale for a very low price.
Opening or extracting a .rar file can sometimes trigger scripts or reveal executable files ( .exe ) that infect your system the moment you run them.
Did you , or are you seeing it flagged by your antivirus software ?
The official game by Crowbar Collective is simply titled Black Mesa . While the developers released a "Definitive Edition" update in 2020, it was a free patch delivered directly through Steam . It is not distributed as a standalone compressed archive like a .rar file.
Look at where you found the link. If it came from a YouTube description, a random Discord server, or an unverified "free games" site, it is almost certainly unsafe.
If you didn't purchase the game through official channels, the safest move is to delete the file and run a full system scan with Malwarebytes or Windows Defender.