Since the game is now considered "abandonware," it is no longer sold on primary digital storefronts like Steam or GOG (where it is currently only on a community "wishlist"). However, you can find it on various archive and preservation sites:
: You can browse the "PC Games 2004" collection for original disc backups and related media. System Requirements Download Besier PC Game 2004
: Originally designed for Windows 98, ME, 2000, and XP. Besieger (2004) - Dreamlist - GOG.com Since the game is now considered "abandonware," it