The magic is US Patent 4,484,419. Known in the industry as the "Telnaes" patent after it's inventor. https://patents.google.com/patent/US4448419A https://pate

The magic is US Patent 4,484,419. Known in the industry as the "Telnaes" patent after it's inventor. https://patents.google.com/patent/US4448419A https://patents.google.com/patent/US4448419A This invention is where slots migrated from physical reels to virtual ones. A reel could now have thousands of "stops" compared to 10 or 20 on the older machines. The physical reels were now driven by stepper motors to show the landing position of that virtual reel. Having virtual reels with many more stops also meant the jackpots could be a lot higher than the typical 1-in-20^3 possibility of a physical reel group. After some time, it was realized that the careful design of these virtual reels is where the slot designer can create many many "oh-so-close" combinations of the physical symbols without making the player land any closer to the jackpot than normal. And that semi-positive reinforcement draws the player in to play more.