Actually, the game itself is fine in Catalina (though there are some graphical, controller and multiplayer issues), as is D:OS EE.
However, Steam is using a less than optimal method of determining whether games are 32 or 64 bit. We are looking in to this, and hopefully Steam is, as well.
EDIT: The configuration of the games in Steam was updated, so they shouldn't be misidentified as 32 bit any more.
The game can be started from Finder: in the Steam library, right click on the game and select Properties, switch to the Local Files tab, click the 'Browse Local Files...' button, and launch the game from there.
Last edited by Raze; 16/10/19 07:07 AM. Reason: issue fixed