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description: Here's an in-depth overview of the game
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# Game Overview

Welcome, brave strategists, to the exciting world of **Blitz Of the Hidden Soldiers**, affectionately known as **BoTHS!**&#x20;

**BoTHS** is an open source chess game, with a twist: you can't see your opponent's pieces _(or at least, all of them)_.&#x20;

## How does that work?

**BoTHS** is an adaptation of the chess variant, [Dark Chess](https://en.wikipedia.org/wiki/Dark_chess), with some modifications. In Dark Chess, players can only view the squares their pieces are "attacking." This means that some information needs to be kept secret from opponents, similar to other chess variants like [Kriegspiel](https://en.wikipedia.org/wiki/Kriegspiel_\(chess\)). While online servers exist where Dark Chess might be played, they come with the standard detractions of trusted systems. We must have a trusted third-party to whom we reveal our private positions. Or must we?

In **BoTHS,**&#x20;

* Players store their pieces and their positions on their devices. When making moves, they only submit commitments to those positions and pieces (i.e. a hash).&#x20;
* To make a move, a player submits a [zk-proof](https://en.wikipedia.org/wiki/Zero-knowledge_proof) that their move is valid (e.g a pawn didn't move 10 squares, or a knight didn't move off the board).
* When a player has made a move, both players submit two things.
  1. A list of squares/coordinates that they can see, given the pieces they have on the board, and a zk-proof to back this up (we call this, a _**player's vision**_).
  2. Given an opponent's vision, a player will submit the pieces on those "visible" squares. Their positions are uploaded to the chess game smart contract, a long with a proof, that they have revealed **all** pieces that are visible.
* Given the position of all the visible pieces, we can tell which two pieces are on the same square. Knowing who made the last turn, we can tell which piece was captured, and by whom.

And some unique modifications of the current implementation are:

* Players are limited to 10 pieces, instead of the standard 16. Why? Purely for performance reasons. Generating proofs is computationally expensive.
* Imagine we could have more piece types. Perhaps a trebuchet? Or instead of a nameless king, let your army be led by the mighty Alexander the Great. Maybe  you'd like a legion of [Mamluks](https://en.wikipedia.org/wiki/Mamluk) to defend your rear and a regiment of [Sagittarii](https://en.wikipedia.org/wiki/Sagittarii) to lead your offensive. BoTHS introduces collectible chess pieces, with unique abilities and effects on your gameplay. Pieces can be purchased with donums, or won during tournaments!

Can you outsmart your opponent and emerge victorious? Dive into the excitement now! Play **BoTHS** @ [https://blitz-of-the-hidden-soldiers.web.app/](https://blitz-of-the-hidden-soldiers.web.app/).&#x20;

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May the best strategist prevail!
