Did anyone encounter this problem? HOMM3 installs and runs fine, except that I can't skip the intro movie - every time I start the game, I must endure the whole movie before I can play. I thought perhaps a firewall is blocking the game from polling keyboard, but that is not the case - I get the same behavior on a completely different computer with no firewall installed. The older versions of the game (with copy protection - that's why I bought GOG version) are able to skip intro easily.

Reinstall it out of C/ to like X/Games/Game-name-2/
and Galaxy to D/Games/GOG-Galaxy/

To make it always work the same start Galaxy in admin... ermm... no. To make same/easier better reinstall GOGGalaxy version to GOG version. And then set game to admin.
Still if you use Galaxy and not want bother yourself with when it must he admin mode - set galaxy.exe to admin in its properties (so, permanently).

Restart Galaxy as admin and validate game installation. And then start game as admin DIRECTLY from Library (to apply galaxy.exe admin argument to game exe automatically)

This just happened to me. I had been running it for months both through GOG Galaxy and separately without GOG from my desktop. Both changed at the same time for me. I'm wondering if it was some OS update that caused this. For some reason, I actually thought it was a mouse problem because I couldn't see the cursor movement or click out of the introduction. Instead I would hit the windows key to get out of the game and close the game from my desktop.

I was having issues opening my Chrome browser at the same time thus I wonder if it was a windows update that did something.

Anyway, out of frustration trying to repair the installation or uninstalling it and reinstalling multiple times, I ended up reinstalling Windows and do a new install of GOG and the game and still had the same problem. I then messaged GOG and they sent me a bunch of what appeared to be can responses, that I couldn't do or didn't apply to me.

I then found this thread realizing it was not a mouse issue for me. I was going to try the editing of the registry that people here were suggesting but since it said it was the introduction that had to play through I let the introduction go all the way to the end. Thus by waiting those minutes, I got the main screen and my mouse finally worked! I thought I had to do this every time unless I changed the registry as people mentioned above, but for some reason, now that I ran the introduction all the way to the end, both my GOG Galaxy version and desktop version does not force me to watch the introduction anymore and my mouse works immediately.

I apologize for the long post. I thought I was going to have to change registry but now every time I open the game up I can skip the intro because I ran the introduction all the way through. I'm running Windows 11 by the way, so just saying from my experience.

I want to thank everyone here for all that was offered. By finding this thread I realized it was not a mouse issue for me and it seems to have corrected itself after running the full introduction to the end.

This just happened to me too. Previously, I was encountering the unskippable cutscene bug, and I made one of the registry edits mentioned in this thread to work around it. When I first started up the game today, the cutscene was once again unskippable, but I let it play through after seeing your post, and now I can start the game without having to watch the cutscene again.

(For me, the cutscene doesn't play at all now. I'm not sure if that's how it is for everyone, or if it's unconditionally skipping the cutscene due to my previous registry edits.)