: You can buy the official version on Steam . This version includes both the main game and the "Deleted Scenes" standalone single-player campaign.
: As a game from 2004, it runs on almost any modern Windows PC.
To download and play safely, it is best to use official digital storefronts. Avoid searching for "download.exe" files from unverified third-party sites, as these often contain malware or outdated, broken versions of the game. Official Download Guide