spellcast-solver

A solver for the Discord SpellCast word game. Give it a board and it finds the highest-scoring words you can spell by linking adjacent tiles.

How it works

SpellCast is a path-finding word game: you spell a word by stepping between tiles that touch (including diagonally), using each tile at most once, and you score letter values modified by bonus tiles.

The solver does a depth-first search over the board, but the key idea is that the search is guided by a trie built from the dictionary. The DFS over the grid and the descent through the trie are the same traversal:

• Each tile you step onto follows one child edge of the current trie node.
• If that child does not exist, no word continues down this path, so the whole branch is pruned instantly.
• Terminal trie nodes carry the full word, so a match never has to rebuild the string it spelled.

This is both cleaner and cheaper than checking a prefix set: extending a path is an O(1) child lookup instead of rebuilding and re-hashing the prefix string at every step, and the trie shares prefixes instead of storing a separate string for each one.

Install

pip install spellcast-solver

The package bundles the public-domain ENABLE word list (~173k words), so it works with no setup. SpellCast does not publish its exact dictionary, but ENABLE is a close match. To use a different list, pass --words PATH on the CLI or load_trie(path) in code.

Usage

spellcast-solve examples/board_redeye.txt --top 10

Output is best score first, with the path and any bonuses applied:

  66  REDEYE           R(2,1) -> E(1,0) -> D(0,0) -> E(0,1) -> Y(0,2) -> E(0,3)  [long]

Board format

One row per line, whitespace-separated cells. Each cell is a letter, optionally followed by /BONUS and/or * for a gem tile. Bonus codes: DL, TL, DW, TW (or 2L, 3L, 2W, 3W). Lines starting with # are comments.

D     E/TL  Y/DW  E     E/DL
E     I/DL  C     A/DL  E
T     R/DW  K     A/TL  A/DL
A     E     G     E     B
B     S     E     W     J

Library

from spellcast_solver import Board, Solver, load_trie

board = Board.parse(open("examples/board_redeye.txt").read())
solver = Solver(board, load_trie())
moves = solver.solve()
print(moves[0].word, moves[0].score)

Scoring

• Each letter has a fixed point value (see LETTER_VALUES in tiles.py).
• DL / TL multiply a single tile's value by 2 / 3.
• DW / TW multiply the whole word by 2 / 3 and stack multiplicatively.
• Words of six letters or more get a flat +10 long-word bonus, added after the word multiplier (so the multiplier does not apply to the bonus).

Letter values are taken directly from the official SpellCast scoring table (see Sources). Any tile value can still be overridden if your board shows something different.

Development

pip install -e ".[dev]"
pytest

Sources

• Discord Wiki: SpellCast (letter values and scoring rules)

License

MIT, except the bundled word list (src/spellcast_solver/data/enable.txt), which is the ENABLE word list and is in the public domain.