It seems most uncommon to me that menu opens on a completely different location then where menu trigger button is located. It is against the best practices of GUI design…
I suggest either the menu is moved to the left side of the screen, or the menu trigger button is moved to the right side of the screen. Either way, the user won’t be forced to move mouse across the whole screen when accessing menu items.
Sorry, I know this suggestion is actualy not about the game itself, which would probably be more desired. So feel free to assign it the lowest priority possible