Bushnell’s Law is the design maxim, associated with Nolan Bushnell and early Atari thinking, that a strong game should be easy to learn, hard to master. The idea is that a player should understand the basic interaction quickly, but continue discovering depth, optimisation, and mastery over time. Barton uses it repeatedly in Vintage Games 2.0 as a historical lens for early arcade design and as a way to explain why games like Pac-Man and Tetris remain legible and compelling. (Barton, Vintage Games 2.0, see source-vintage-games-2)
The law is useful as a design heuristic, not a universal rule. Barton specifically treats street-fighter-ii as a famous counterexample: it is not easy to learn, but its social context and competitive depth made it hugely successful anyway.
Related: game-loops, smooth-learning-curves, systemic-depth-elegance, street-fighter-ii