That’s right. Despite being a cult classic, Pandemic Studios never ported the game to Windows. You can find its janky sequel ( Mercenaries 2: World in Flames ) on PC, but the original, superior "Playground of Destruction" remains locked to the PS2 and original Xbox.
Avoid the PS2 ROMs from sketchy pop-up ad sites. Look for the "Redump" set on the Internet Archive. Pair it with a controller (this game is miserable on keyboard and mouse), turn up the internal resolution to 4K, and prepare for the most chaotic military sandbox ever made.
The Colonel wants his 52 cards back. Go get them.