Busy Beaver (Turing Machine)

The Busy Beaver game asks a simple question: What is the maximum number of 1s a Turing machine with N states can write on an initially blank tape before halting?
This is a visualization of the tape history of a 3-State Busy Beaver, which writes exactly six 1s and halts after 21 steps. The head sweeps back and forth, altering its environment according to rigid rules.
The tape's history is laid out vertically: Time flows downward. The current head position glows bright green.