PeerPlay
How the engine maps to the rule
12 cylinders, 12 testers. New personal Google Play developer accounts (created after November 13, 2023) need at least 12 testers opted in to a closed test for 14 days in a row before Apply for production appears.
One cycle, one day. A four-stroke cylinder fires once every 720° of crank. Here that is one day, so every tester "fires" once a day: intake, compression, power, exhaust.
A tester leaves. With spares, a spare tester is already opted in and takes the cylinder, so you stay at 12 and the day count keeps going. Without spares, the cylinder goes cold, you are at 11, and the run stalls. In Play Console the count can start again once you are back at 12.
The engine itself
The motion is computed, not animated by hand. Bore 89 mm and stroke 80.4 mm give 0.500 L per cylinder, 6.0 L in total. Each piston follows the slider-crank equation x = r·cos θ + √(l² − r²·sin² θ) with r = 40.2 mm and l = 150 mm. The banks sit 60° apart on a 120° crankshaft, so one cylinder fires every 60°. Chamber pressure is a simple polytropic model (compression ratio 11:1, n = 1.3), good enough to show the loop collapse when a cylinder misfires. Drop-out days are random and the number of drop-outs is yours to pick: we don't have a real drop-out rate to plug in.
To check the real dates of a test you've already started, use the Closed Testing Checker. Play Console's counter on your app's Dashboard is the source of truth.