Microsoft DirectX® is already included in Windows XP Service Pack 2, Windows Server 2003 Service Pack 1, Windows Vista, Windows 7, DirectX End-User Runtimes (June 2010) - Microsoft
Because DirectX 8.1 is over 20 years old, the official "8.1-only" links are largely dead. Use these reliable alternatives: download directx 81 offline installer link
Here is an industry secret: The contains every single DirectX 8.1 and DirectX 8.0 DLL. Microsoft consolidated legacy runtimes into the last DirectX 9 redistributable. Microsoft DirectX® is already included in Windows XP
...you will likely run into issues on Windows 10 or Windows 11. These games were built for the architecture of DirectX 8.1. While Windows is generally backward compatible, sometimes specific library files ( .dll files) get corrupted or go missing, necessitating a manual reinstall of the legacy runtime. Windows Server 2003 Service Pack 1