Simple interactive background app for MacBook

This is a focus/efficiency app that I have fully prototyped, and find very helpful for my own work. However this prototype has a number of important bugs, and I believe fixing them requires a less hacked-together solution. The goal of the project is to have an app (presumably a menu-bar app) that will launch an EXTREMELY simple minigame, whenever a particular hotkey combination is pressed. (The game: press a key, when appropriately prompted by a simple geometric animation.) It should be able to do this no matter what application is being run. The difficulties (for me, prototyping in python) involve getting system permission to allow globally bound hotkeys, while simultaneously packaging this functionality into a functioning .app, as opposed to running it all with local settings and scripts, so I'm looking at Cocoa as a more native solution, but am not a Cocoa developer.