Thanks for playing the game, and glad you like how I translated the collar to the game!
Do you remember what upgrade killed you? I think the only way you should be able to die from upgrades at the moment is buying a shop item when you dont have enough money. I think the player being able to kill them self from wrong decisions is in the spirit of a roguelike/lite, but I should give a proper indicator that your about to lose 2 INT from taking an item in the shop since even I have missed it on occasion.
Thanks again for playing and for the feedback