There are two convenient ways to install HotA on Linux.
Steam allows you to install HotA both from its own game store and via the standard installer.
Heroic Games Launcher allows you to install HotA both from the GOG game store and via the standard installer.
Choose whichever method is more convenient for you. Both installation methods work on Intel and AMD processors (x86_64 architecture).
Steam
Download and install Steam from https://store.steampowered.com/about or from your distribution’s repository
Launch Steam and log in
Installing the Steam version
Find Heroes of Might and Magic III: Horn of the Abyss in the Steam store and install it
Click LIBRARY → Home → Heroes of Might and Magic III: Horn of the Abyss → click PLAY
Installing the standard version
Click Add a Game → Add a Non-Steam Game… → Browse… → select the Heroes of Might and Magic III: Complete setup file (.exe) → Add Selected Programs
Click LIBRARY → Home → select the added installer in your games list → right-click it → select Properties…
Go to the Compatibility tab → check Force the use of a specific Steam Play compatibility tool → select Proton Experimental from the drop-down list → close the window
Click PLAY → complete the installation
Again, select the added installer in your games list → right-click it → select Properties…
Go to the Shortcut tab → in the TARGET field, click the Browse… button → select the HotA setup file (.exe) → close the window
Click PLAY → install HotA into the Heroes of Might and Magic III: Complete folder
Again, select the added installer in your games list → right-click it → select Properties…
Go to the Shortcut tab → in the TARGET field, click the Browse… button → select h3hota HD.exe in the HotA folder → then enclose the game path in quotation marks
""In the START IN field, click Browse… → select the folder where HotA is installed → close the window
Click PLAY
Heroic Games Launcher
Download and install Heroic Games Launcher from https://heroicgameslauncher.com or from your distribution’s repository
Launch Heroic Games Launcher → go to Wine Manager → Proton-CachyOS and install Proton-CachyOS-latest
Installing the GOG version
Click Log in → GOG LOGIN → log in to your GOG account
Click Library
Find and install Heroes of Might and Magic III: Horn of the Abyss
Launch the game
Installing the standard version
Click Library → ADD GAME
Click RUN INSTALLER FIRST
Select the Heroes of Might and Magic III: Complete setup file (.exe) → complete the installation
Click RUN INSTALLER FIRST again
Select the HotA setup file (.exe) → install it into the Heroes of Might and Magic III: Complete folder
Click Select Executable → select h3hota HD.exe in the HotA folder → click FINISH
Launch the game
Additional Notes
Use the ADD GAME button to create shortcuts for editors (e.g., the map editor).
To do this, select the editor’s .exe file in the Select Executable field.