Thanks for playing the game and sharing thoughtful feedback! I'm sorry the 'killswitch' code seems to have messed up - I will need to playtest and see if the tilde (~) doesn't work for other keyboard layouts. It's always a bit annoying when things work for one but not for someone else, as it seems you're not alone with those issues! Thanks for persevering though and I'm glad you generally had fun! Please let me know if the same issue occurs on the desktop version if you're so inclined to give it a go sometime.
Also, as a fun trivia, the calculator game is Digi Invaders - it was a real game you could play on an 80s Casio MG-880! Check out a video here: