Thanks for the kind words! I was initially planning to have an invisible monster you could only detect using the geiger counter, with the goal of leading it into a trap or something. But it was clear I wouldn't have enough time to pull that off, so reduced the scope and made this.
I think there is a bug where you can turn and move at the same time with the right timing, might have been that which caused you to slip through the collision.
Anyway glad you enjoyed it!