I installed original AoE plus the AoK expansion then the UserPatch 1.1 R4 HD onto Windows 10 Pro X64. That works great and looks great.
So then I install AoE 2 + Conquerors from my old AoE Gold set, then the last update for Conquerors so the UserPatch for that will install. Works great, looks great, but unlike for AoE 1 the setup and menu screens haven’t been given the HD treatment.
Unfortunately installing AoE2 breaks AoE1! When I go to start the campaign it crashes. empires.exe the application has requested the runtime to terminate it in an unusual way.
Jumping into a random map works, but that’s it. I didn’t try playing an AoE1 campaign (hadn’t even saved a game) after installing AoE2 + expansion before installing the UserPatch for it so I don’t know if it’s AoE2 or its UserPatch that breaks AoE1.
Edit: Reinstalling AoE1 + expansion + last official patch + latest UserPatch does NOT make any difference. It passes the file check, passed it before.