Wish I'd gotten here a few hours sooner to provide some input on this. I adamantly disagree with the user above re the mouse. While CTRL+<any letter> is going to be a bad time because of keyboard shortcuts (although I got a laugh out of one game that forced you to reconfigure the controls as a game mechanic... and tricked the player into bookmarking the game half way through), the mouse is the wrong control to use for this. A mouse isn't a button, its primary function involves positioning. By using the mouse as an input, it provides the impression that interactions should be oriented using the mouse - which is an entirely reasonable UX, but obviously not what you decided on for this game. And unnecessary mouse use makes a game more difficult to play on a laptop with a touchpad.
I see you left CTRL+arrows in as an alternative, and that works perfectly fine, so adding the mouse as an alternative here didn't hurt playability (although it's still not the right use for a mouse). But don't let the previous commenter's opinions fool you into thinking the mouse is actually a good/better "button" as you make future updates/games. From a usability perspective, using it for that purpose is wrong, because it implies a control scheme that it isn't being used for, and I spend WAY too much time explaining this to developers.
HOWEVER - two handed keyboard use then would be aided by not needing the mouse for menus.