Chess engine modification

Hi there, I am interested in modifying a chess engine to play a chess variant I am working on. The variant only requires 3 pieces to have their move modified. All other chess rules stay the same. Any thoughts on an engine that would be fairly easy to modify, not have licensing contraints and fairly straight forward to interface to via an API or similar?

https://www.chessprogramming.org/JavaScript - there are links to some Github repos on this page.  The engine can be run inside the browser.

Thanks Timothy. One of the challenges is finding an MIT or LGPL licensed engine. Fairy stockfish looks good but it is a GPL license so we would have to open source our front-end which we aren't keen on doing.

I don't know how unusual you want these three pieces to become. But there already exist several engines that are configurable for playing a large variety of variants: Fairy-Max, Nebiyu, Sjaak II... These use the text-based XBoard protocol as API, and can be configured by providing a definition of the chess variant(s) you want them to play (board size, participating pieces, how each of these moves) in a separate text file. They support a wide range of unorthodox pieces (arbitrary leapers and sliders, hoppers, lame leapers, sliders with bent trajectories...).

Since the game definition for these program is just data they operate on, and not part of the program, it would not be covered by the program license. You can use the program unmodified, so you wouldn't care whether it is GPL or not. You would own the copyright on the game definition, and could subject its use to a license of your own choice. With chess engines the AI and the front-end are separate programs anyway, so you can use a GPL engine in a closed-source front-end. Or is the problem that you are developing for iOS, which doesn't allow inter-process communication? Fairy-Max is public domain anyway.

The best place to discuss such matters would be the talkchess.com forum, where all the chess programmers are.

Thanks Mr Muller. Great insight - really appreciate it! Will post on TalkChess now that they have approved my account request

Your engine may be useful to play human vs engine or to use it as an analysis tool.

If you willing to adopt my variant in your server i will appreciate it.

Hi 50Mark, the project is funded for a specific purpose and has strict parameters and funding. So no piggy-backing allowed sorry.

so were u able to develop that?