The Game of Nemoroth

The Game of Nemoroth, created by Ralph Betza in 2002, is the most complex playable chess variant ever created. Based on a cosmic horror theme, standard chess pieces are replaced with new pieces exhibiting side effects and complex interactions with each other. Multiple pieces can occupy a square and check is replaced with "compulsion," which can happen to any piece and to multiple pieces at the same time.

Twenty years after the original game's creation, the first ever computer implementation of Nemoroth has arrived, complete with AI opponent. The move generator and AI are written in C++ and compiled to a Web app via WASM, with a GUI written in TypeScript. There are many areas for improvement in the speed and playing strength of the AI, which is currently the crudest possible alpha-beta search with minimal optimizations.

Read the rules.

Changes and clarifications from the original game

There is only one restriction that is distinct from the original game: the Go Aways always push in a fixed order, clockwise from top. This is a placeholder and will be addressed in a future version -- I've procrastinated on it mainly because it's a UI/UX nightmare.

In addition, there are a number of ambiguities which I addressed:

Can a petrified Human, pushed to the furthest rank, unpetrify when it becomes a Zombie? Yes. This makes petrified Humans more interesting.

Can a Wounded Fiend approach and then flee a Ghast in the middle of its path? No. Passing over Ghast squares is against the spirit of how riders work, and inconsistent with how they interact with Basilisk or ichorous squares.

If multiple Zombies are pushed on an ichorous square, are they all dissolved? Yes. If only one Zombie were dissolved, it leads to the question of which one?

What if a square with multiple Zombies is ichorated? Same thing, they all dissolve simultaneously.

If a Wounded Fiend and a Zombie are on the same square and the Wounded Fiend leaves, depositing ichor, does the Zombie dissolve? Yes. The Zombie/ichor interaction is both active and passive.

A mobile piece other than a Zombie is compelled to move off an ichorous square. Is it a saving move to push a piece from an ichorous square to another ichorous square? No. Pushing from a multiple occupancy square to another multiple occupancy square is not a saving move, and neither is pushing a piece from a Ghast square to an equal distance to the Ghast.

If a Wounded Fiend leaves a square that already contains ichor, does the ichor stack to more than 10 moves or does it reset to 10 moves? It resets to 10 moves.

If a Zombie is pushed into an ichorous square containing both a Leaf Pile, is the Zombie dissolved or is it engulfed? Dissolved. Think of ichor as covering the entire square while the Leaf Pile occupies only part of it, so the Zombie would come in contact with ichor before the Leaf Pile.