Been trying to set up Might and Magic 8 for a merge mod run or twelve. However, none of the Proton or WINE versions in Heroic fully work. I've played Merge/MM8 before under normal WINE, so there's a disconnect between the Proton here and WINE that you can get from WINEHQ.
What's happening is that some keybindings are simply broken. Attack, Quick Spell, Inventory, and Jump notably. Which makes it rather difficult to play the game. From searching, this has been a continuing issue with Heroic for a few years, though most of the posts are about Steam Decks and I'm just running a regular desktop (Mint 22.2 Zara). I've attempted to use Proton-Latest, Proton10-20, 9-27, 9-4, and in Wine-GE Latest, and 7-43. None have any improvement; they all disable some functions in game.
The keys themselves work in the settings when rebinding them, or when naming characters, but when actually playing the attack, quick spell, and jump functions are completely disabled.
If I ignore heroic entirely and install MM8 via the offline installer into WINE 9.0 (yes outdated, but it's the default in the repository and I didn't feel like doing the effort for the latest for essentially a test run to narrow down the problem), it works fine. I can jump, go straight to inventory, cast quick spells, and attack without worrying about it.
Adding the installed version from outside Heroic into the Launcher, it just crashes; it will not load. Despite working in WINE perfectly well, and Heroic able to load MM8 installed directly even if it's unplayable.