D20 Craps

That question got asked at a Dragon Con afterparty, more or less, to a friend who teaches math for a living. Neither of us could let it go for the rest of the night, and I was still turning it over on the drive home.

I went home and worked out a full rule set. Roll 2d20, and 21 becomes the new 7 — the number that wins you the come-out and the number that craps you out once your point is set. Point bands. Hardways from 1-1 all the way to 20-20. Field bets. True-odds plays with zero house edge, because the math is the entire appeal and rigging it would be missing the joke.

Then I looked at it and thought I could build this, so I did. Same heartbeat as the felt in Vegas, rebuilt for people who would rather roll a d20. Roll the bones, find your point, and pray you don't see a 21 too soon.

This is the only one on the bench that's properly live, at d20craps.com, built in Next.js and Three.js. A Godot build for mobile is the plan rather than a promise.

For about four hours on 10 August the dice were stuck — every roll came back a 2, because the physics library had quietly stopped talking to the renderer and both dice were being read before they'd turned. The link came down for exactly as long as that was true. It's fixed: the dice tumble and settle on real faces now, and the roll is a real roll.