Originally posted on r/ComputerChess (June 18, 2026), while building Chexx — chess where every move transmutes your pieces.

I'm experimenting with a chess variant & wanted some engine-oriented perspectives.

Core rule:

Whenever a Major/minor piece moves, it transforms into another piece type (randomly selected among legal value-capped outcomes: e.g. Chexx-VC-54 ~ total value of each side < 54).

That means:

• material evaluation becomes less static
• move consequences can alter future mobility in unusual ways
• piece-square tables become less reliable
• Bakes a chance element into the game making it more fun & unpredictable

I'm wondering how engines would adapt.

Some thoughts:

• Would alpha-beta suffer more because tactical trees become harder to prune?
• Would MCTS perform better in this environment?
• How much harder would evaluation design become compared to standard chess?

It feels like the branching factor isn't necessarily larger, but the state volatility is.

Curious whether anyone here has worked on similar transformation-based variants.

Where this went: the variant shipped as Chexx — a 3D browser chess game built with Three.js + TypeScript, w/ vs-Computer (Novice / Skilled / Master) & 2-player hotseat modes. Source on GitHub.