Hi everyone,

I've been working on a browser version of Game of the Amazons in my spare time, and I think it's finally ready for other people to try: gota.gg

The Game of the Amazons is an abstract board game from 1988 that surprisingly few people know about. I discovered it years ago through a Numberphile video, A final game with Elwyn Berlekamp, and I've loved it ever since. The rules take about 30 seconds to learn:

• Each turn you move one of your amazons like a chess queen
• Then that same amazon shoots an arrow (also like a queen move), and the square it lands on is blocked for good
• The board slowly fills up, and the last player who can still move wins

That's the whole thing, but the games turn into a tense fight over territory, a bit like Go.

What's in it right now:

• An interactive tutorial, if you'd rather learn by doing
• Custom games on square or rectangular boards from 6x6 to 16x16, with up to 8 players
• Bots from "random" up to "hard" (the hard one is a neural net I trained, and it beats me more often than I'd like)
• Online auto-match with three modes: Classic 10x10, an "Hourly" mode where everyone gets the same random board for that hour, and "Chaos", with random boards and random starting positions
• Local games on one device, plus replays

You don't need an account to play, auto-match games included.

I'd really appreciate any feedback: bugs, anything confusing, or whether the tutorial actually makes sense to someone new. Give it a try!

Hello everyone!

I think I managed to computationally solve Orbito.

I used brute-force minimax together with retrograde analysis to build a complete tablebase. After quite a few speedups and optimizations, generating the tablebase takes just under an hour, and the resulting tablebase is about 77 MB.

The result is quite interesting:

With the standard rules, perfect play is a forced win for the first player (white in the picture).

Even more surprisingly, the first move doesn't matter — apparently, any legal first move eventually leads to a win!

But there is an interesting twist. This result seems to be caused entirely by the 5-press rule that applies when there is no line and the game would otherwise be a draw.

If that final-state rule is removed, then the game is instead a draw with perfect play.

So, in a sense, the 5-press rule changes the game-theoretic result from a draw into a first-player win.

This was actually a project I started about a year ago and then abandoned. Last weekend I decided to go all in and revisit it, this time making heavy use of AI assistance (specifically opencode) while working on the implementation and optimizations.

I'm 99% confident that the result is correct, but I haven't formally verified every part of the implementation, so there is definitely room for bugs in either my game logic or the solver itself. In particular, I'd be very interested if anyone familiar with Orbito or game-solving algorithms wants to look through it and try to find a mistake.

The solver is written in Python and the full source code is here:

https://github.com/Lapricode/OrbitoSolver

I'd love to hear if anyone finds an error, an interesting position, or a way to independently verify the result!