This is not sha3 it's a Keccak Implementation that follows the Keccak-f[1600] specification with 24 rounds.
It has a sponge construction witch absorb-squeeze paradigm with 136-byte rate, it implements Keccak padding (0x06 then 0x80), the Proof-of-Work iterates nonces until hash meets target difficulty and it uses little-endian byte order throughout to match WASM stuff.

I can probably provide a working source code in C or Cpp or Rust if someone feels the need, may take a bit of time. Keeping the wasm closed source is not the way I like it.