Arcade machines have long mastered the art of keeping players engaged by dynamically adjusting enemy AI based on their skill level. Unlike modern games with complex machine learning, classic arcades relied on clever programming tricks to create the illusion of adaptive intelligence.

One common method was through difficulty scaling tied to player performance. If a player was clearing stages too efficiently, the game would increase the speed, aggression, or quantity of enemies. For instance, in shooters like "Galaga," enemy formation patterns become more complex and unpredictable as the player progresses. The AI doesn’t "learn" in the true sense but follows pre-programmed behavioral tiers that activate based on score thresholds or survival time.

Another technique was the use of rubber-band AI, famously seen in racing games like "Out Run," where opponent cars would subtly slow down if the player fell behind or become more aggressive if the player led by too much. This ensured tension remained high regardless of skill.

Arcade cabinets also employed hardware limitations to their advantage. With finite memory and processing power, developers designed enemies with predictable but adjustable patterns. For example, in "Pac-Man," the ghosts each follow distinct logic—Blinky chases directly, Pinky ambushes, Inky switches between strategies, and Clyde acts randomly. As the player advances, their speed and coordination increase, creating a seamless difficulty curve.

Ultimately, arcade AI wasn’t about true artificial intelligence but smart design that responded to player input in real-time, making every playthrough feel uniquely challenging.