Board Game Arena

I'd suggest it at many times I have bought instead of sell and vice versa which was game breaking... Hope undo can be made possible for Clans

I'm sorry that that happened to you, but isn't already so that you need to click 2-3 buttons to buy or sell? Therefore, I don't think this is really necessary.
I mean, in some other games you can do something wrong with just one click - here you always need two.

Just had a game ruined by exactly this. And it happens multiple times per game, EVERY game I've played (and not just to me). It so desperately needs an undo / restart turn function. It's a complex game and having no way to change your mind after starting a certain action is extremely limiting and, dare I say, game breaking. I honestly doubt I'll play this again on BGA purely because of this issue.

I completely agree with OP. this is the only complex game on BGA that I can think of that doesnt have an undo button.

Example: I am playing a turn based game and so I had some time since my previous turns. I built a building specifically to get the neighbourhood bonus, not realising that I had no merchants left. A simple mistake and one that in real life you would just pause, realise the move wasnt valid and buy a merchant. Instead I couldnt undo and basically my whole game is ruined because of a small error.