Hi null! Sorry for the confusion, and thanks so much for playing! Demon's Keep uses a command unique to the modern steam version of RPGMaker 2003 to automatically set the ATB to "Wait" instead of "Active". EasyRPG doesn't recognize this command, so it stays set to "Active" mode, increasing the number of enemy turns. There's no menu option to change it because I didn't like how the game played on Active, and I didn't consider how that would impact EasyRPG players.
Like my game Facets, Demon's Keep uses a hacked executable to remove the Autobattle and Row commands. If it weren't for that, I'd try to support EasyRPG better, but as is I'd rather formally state that EasyRPG is not supported for Demon's Keep. I've added a note to the page to make that clearer for new players.