If you want to try something free and mind numbingly simple, but DnD related and licensed, check out Idle Champions.
But do not click on the cash store or even peek at the cost of all the DLC ... Its on the same level as Train Simulator, but all the purchasable stuff is optional / pay2shortcut rather than pay2win.
Its fun and addictive for about a week or two then you will hate yourself for wasting so much time with a pointless clicker game.
Or if you want something thats waaaay different but even creepier than mindflayers devouring brains ...
https://www.youtube.com/watch?v=9QdGzJhunb4
