I was able to run Age of Empires 2 on Windows 11. It didn't like running on an ultrawide, but it worked well enough at smaller resolutions.

The 2006-engine version of Half-Life 2: Episode 1 runs on Windows 10/11 with no configuration [1], outside of getting Steam to download it. I recall installing The Elder Scrolls IV: Oblivion on a Windows 11 machine, which just needed Directx 9c to run.

[1] https://steamcommunity.com/sharedfiles/filedetails/?id=28643...