Fascinating!
Retired engineer discovers 55-year-old bug in Lunar Lander computer game code | Ars Technica:
As mentioned in the quote above, the root of the problem was a simple computational oversight—a missing division by two in the formula used to calculate the lander’s trajectory. This seemingly minor error had big consequences, causing the simulation to underestimate the time until the lander reached its lowest trajectory point and miscalculate the landing.