They do know that physical turtleman is an immovable point because I explicitly state that in the invite.
Catching up on the thread, but can I just check what you mean here?
I agree that if the premise is explicitly 'you are all dwarves' or something, a player saying 'hey can I be a tortleman' is not cool. The GM is absolutely right to say no. If a player has a very good explanation for how such a character might fit with this premise then maybe asking is OK, but they should probably still expect to be shot down.
I agree that if the premise is explicitly 'no tortlemen', like there is a specific list of banned races, or if you're playing in a heavily pre-defined setting like Middle-earth or something where tortlemen do not exist, again maybe there is room for a player with a very good explanation to ask, but they should expect a no.
My understanding of your situation was more along the lines of 'this is a fairly generic D&D world and the main races are elves, dwarves, humans, and tieflings, but with a twist'. In that case, where you haven't explicitly ruled out tortlemen, that's where I think a flat refusal to even consider them is unreasonable.
So you have an explicit list of 'not allowed' races that you give to players and 'tortlemen' are on that list?


