In 1962 Tibor Radó asked a deceptively simple question: among all Turing machines with n states that eventually halt, which one runs the longest? Call that number S(n). For two states the answer is 6 steps; for three, 21. Both are drawn here as ghost ticks for you to chase.
Radó proved S(n) is uncomputable — it grows faster than any program could predict. The reason is the halting problem: there is no general procedure that, given a machine, decides whether it will ever stop.
You feel it at the odometer. A machine still running at ten thousand steps might halt on the next one, or never — and no gauge on this panel can tell you which. Radó's theorem says the gauge you wish you had cannot exist. Most machines die at once; a precious few run absurdly long and then, astonishingly, stop. Breeding those is the whole sport.
The simulation stopped unexpectedly — the lesson continues without it. You can move on; nothing you did was wrong.