High-Frequency Chess

Standard chess, but instead of a clock each engine gets a fixed budget of 150,000 CPU core cycles per move.

Rules

Rule	Value
Budget per move	150,000 core cycles (~30µs at 5GHz)
Carryover	None
Overrun grace	2,000 cycles
`hfc_init` budget	1,500,000 reference ticks
Max game length	400 plies, then drawn
Toolchain	Pinned in `rust-toolchain.toml`
Dependencies	None beyond `hfc-rules` and `hfc-abi` from crates.io
Build scripts, proc macros	Forbidden
Lockfile	`Cargo.lock` must be committed
Source size	10 MB, 2,000 files, measured after decompression
Max binary size	16 MB
Entries per account	4
Submissions	one per account per 120 seconds

Your engine

Rewrite entries/example. Each engine runs in its own single-threaded process with no I/O. Memory is capped at 256 MB.

Forfeits

Condition	Result
Spent more than budget + grace	Forfeit the game
Illegal move	Forfeit the game
Returned 0 with legal moves available	Forfeit the game
Segfault, panic, hang	Forfeit the game
Missing or mismatched ABI symbols	Rejected at load
A quarter of the match's games failing, 200 minimum	Forfeit the match

Testing locally

Clone the repository, ./build.sh, then:

./target/release/harness verify entries/example/target/release/libexample_engine.so
./target/release/harness match entries/example/target/release/libexample_engine.so \
    build/reference.so --games 2000

The harness names any perf permission it is missing. Cycle counts only compare within one microarchitecture.

Submitting

git archive HEAD:entries/example --format=tar.gz | curl -f -X POST \
  -H "Authorization: Bearer <your-api-token>" \
  "https://hfchess.com/api/submit?kind=tarball&name=my-entry" --data-binary @-

or upload the same tarball through the dashboard, which shows your API token while you are signed in. Resubmitting a name rerates it from scratch.

The ladder

The scheduler picks all matches. Each opening from book.txt is played twice with colours reversed. Ratings are relative to reference at 0.

API reference: /docs/api.