Slots

Pull the 3-reel one-armed bandit. Line up sevens and bells across the payline to hit the jackpot.

Modern slot machines have no physical relationship between the reels you see and the outcome. A random number generator picks the result and the animation is a presentation layer, which is why stopping the reels early changes nothing at all.

The design technique worth knowing about is the near miss: symbols are weighted so that two jackpot symbols with the third just above the payline appear far more often than chance would produce. It reliably increases play, which is why several jurisdictions regulate how far it can be taken. Return percentages are typically 85 to 98, and unlike video poker they are usually not disclosed on the machine.