Doom Captcha (2021)

Original Article ↗ Hacker News Discussion ↗

Overall Reception

  • Many find the Doom-themed CAPTCHA fun, creative, and a welcome change from standard image CAPTCHAs.
  • Some express nostalgia for Doom and appreciate touches like music and references to classic mechanics.
  • Others are underwhelmed that it’s more a simple shooting gallery than “real” Doom, and note it’s a few years old.

Usability & UI Confusion

  • A large subthread criticizes the start UI: users often click “click to start” text instead of the sound ON/OFF buttons, assume it’s broken, and leave.
  • Several propose small fixes (e.g., “Click to start:” label, “Start with sound / Start without sound” buttons, separate “Start” button plus a sound checkbox).
  • Some argue this confusion is non-trivial and detracts from the demo; others say it’s minor and that nitpicking UI distracts from the idea itself.

Security & Bot Resistance

  • Consensus: the author explicitly says it’s “just for fun” and easy to break.
  • Multiple comments argue it wouldn’t stop serious bots, and that bots and AI already defeat many CAPTCHAs.
  • One commenter describes quickly scripting a vision-based solver using fixed enemy colors and limited regions.
  • Others discuss how stronger versions might work: canvas rendering, varying rules (shoot X, not Y), rate limits, cursor-movement analysis, server-streamed enemy positions.
  • Some suggest that obscurity and interaction complexity might still put it on par with or better than some standard CAPTCHAs for low-stakes use.

Comparisons to Other CAPTCHAs

  • People contrast it with Google’s CAPTCHAs, which some find increasingly unreliable or difficult for humans.
  • Several share experiences with alternative CAPTCHAs: simple math questions, empty “honeypot” fields, lore questions, calculus problems, esoteric-language puzzles.
  • There’s concern that making puzzles too hard filters out humans more than bots, especially when attackers can combine OCR with LLMs.

Ideas, Variants, and Extensions

  • Suggestions include:
    • Full 3D or WebAssembly Doom, or Freedoom assets to avoid copyright issues.
    • Men in Black–style “identify the real threat” modes.
    • Hostages/barrels you must not shoot.
    • WoW-style fishing mini-game CAPTCHA.
    • A Doom progress window mini-game during long tasks.
  • Several note it’s easy to “spam click” to win, suggesting adding fire-rate limits or changing enemy positions.