Are you sure about that? I remember a discussion i had long time ago with an usability person and i think he mentioned showing and hiding menu actions is usually not the best of the ideas because it confuses the user that things the action was there and when it isn't gets confused and thinks it's either somewhere else or that he misremembered, but if instead the action is disabled, usually the user thinks "ah, i need to move to a different state to enable this".

But this was a discussion from almost 10 years ago, maybe the usability recommendations have changed or maybe i didn't even understand it correctly :D

I agree with the general UI best practice. But this change is different. As far as I understood the program, there are two modes: "Enter/edit a game" and "Play the game". The "Check" action is currently always grayed out during "Play the game" because it makes no sense there. And the "Hint" action only makes sense when playing the game not when creating one. In either mode, the user gets more confused because a deactivated button indicates that it might come available which is not true (as far as I can see it).

Well, you're the de-facto mainitaner now, so i'll have to trust you, i'd say if noone complains in a week, just commit this. (with the two small things fixed if possible)