The breadboard version of the light trigger worked so I built a more usable version of it for the game prototype. I’ll do a full PCB version next time I do a run. This pass includes a larger potentiometer because the sensitivity will need to be tuned for the lighting at each installation.
It worked on my desk right away without using the laser pointer. My office is lit with overhead spotlights, and they throw an adequate shadow for testing purposes. The RC circuit delivers a pulse of about 120ms, which in my current software build is about four passes through the inner game loop. I can shorten that down by changing the resistor, but right now the code just cares about the leading edge.
The hand wiring step works easily with small prototyping boards I bought off of Amazon.