Based on the book The Island of Dr Moreau, Heathen is one of the most original games I've ever played, although, all the excitement stops there...the game is in Early Access since 2018, without any updates since then, and can now be considered abandoned. I cannot recommend it only for that reason, and even if you don't mind it's price, the fact that it will probably remain in a cliffhanger forever, is just heartbreaking...
It runs perfectly on Steam Deck as you can see by pressing the link below;

https://youtu.be/wwlk1rbYREA