Show HN: Probabilistic Tic-Tac-Toe

Original Article ↗ Hacker News Discussion ↗

Overall Reception

  • Many find the idea “fantastic,” “brilliant,” and surprisingly deep for Tic-Tac-Toe.
  • Several comment that randomness plus strategy makes it compelling, but also occasionally frustrating when losing high-probability moves.
  • Some feel the AI is weak or makes “obviously bad” plays, while others report being consistently beaten or going roughly even over many games.

Gameplay & Strategy

  • The game forces players to think in probabilities rather than classic Tic-Tac-Toe patterns.
  • Some initially overvalue the center; later realize square odds change every game and that corners and “forcing” the opponent onto bad squares can be superior.
  • A key tension: sometimes it’s optimal to let the opponent attempt a dangerous square if the “bad” outcome probability is high.
  • Neutral rolls (“nothing happens”) significantly affect tempo and who is forced to make the final, risky move.
  • Players note that even doing “everything right” can lose in a single game, but skill should dominate over many games.

UI, Performance & UX Feedback

  • Multiple users report slow initial load, a dark/blank screen, or heavy resource usage; Unity is seen as overkill by some.
  • Dice-roll animations are praised visually but widely criticized as too slow for repeated play.
  • A fast-forward button was added; some think 2× is too fast, others like 3×.
  • Requests include: instant-skip on dice, a line through three-in-a-row, clearer tie indication, and a mode with lower latency.

AI & Optimal Play

  • The built-in AI uses simple heuristics based on local probabilities and line potentials; it sometimes misses blocks or picks weaker squares.
  • Several commenters work on stronger solvers: minimax, expectiminimax, value iteration, Markov-style reasoning, and linear programming.
  • There’s debate over whether simple greedy expected-value heuristics are nearly optimal versus needing deeper tree search.
  • One detailed probability spec for board generation is shared: per square, neutral, good, and bad chances are randomized with constraints, mapped to d20 faces.

Extensions & Variants

  • Ideas include probabilistic versions of Connect Four and Battleship, alternate rules modeling “rich get richer” dynamics, and a physical travel version using tiles and a d20.
  • Related games mentioned: “Quantum Tic Tac Toe,” “incomplete information” Tic-Tac-Toe, and other probabilistic or quantum variants.