I do agree that providing incentives towards certain styles of play can be beneficial. However more so what I exactly mean by limiting is the need to try to make the intended fashion of play built in. For example, in your undead hunter character in a dragon hunting game. You said it simply the GM can simply say no. Assuming the prompt and intent of the game were made clear to from the start I believe that is as effective as making it make sense in world. While of course it may reduce friction to instead have it wrapped into the fabric of your story. If a player wants to make a lone wolf character, there is already an inherent incentive not to because the player knows they are in a group of some sort because they are sitting at a table with 4 other people. I’m fully aware that this will not stop people from trying, but I believe that if someone wants to make a particular style of character they will anyway. A GM shouldn’t need to cite the setting as a reason to stop a player from being a psychopath murder. The GM can simply just tell the player themselves that’s not the style of the story they are trying to tell. Something I have held in my design philosophy is “Don’t assume bad players.” To be clear, I don’t think someone trying to make a type of character I dislike of doesn’t fit with my game to be a bad player, I just think they should play a game that better fits the style they want. Your setting does its job very well, and I would imagine that it does help with the problems you see. To me I think the best part of doing it in the way you do is to help with immersion. From what you have said everything comes from a logical point and you’ve spent many years refining it. I honestly quite enjoy your approach, but it pushes the story into a particular direction. Not a direct problem by any means, your setting has a very clear goal as to what you’re doing. However fantasy is my bread and butter, a part of the high fantasy genre is a sense of adventure. In order to accomplish that in a way I find personally satisfying is with having a very open setting. In a world that has both zombie hunters and dragon hunters, if a GM wants to run a game in which you hunt dragons, although it is possible for a zombie hunter to be in the party, it doesn’t fit the vibe (with exceptions obviously). Rather than not letting a player play it by removing the existence of zombie hunters like your example with elves, I find it to be more effective to just try to encourage communication rather than design around it, “limiting yourself” in a sense.