Chess engines: Heimdall 1.0 NNUE

Heimdall - UCI chess engine written in Nim.

Author: Mattia Giambirtone

More info
Heimdall is available on Lichess under its old name (Nimfish), feel free to challenge it! I try to keep the engine running on there always up to date with the changes on the master branch

v.1.0:

NNUE go brrrr

So, we're back at this shit eh?

A lot of stuff happened since the release of Heimdall 0.4: a beta version of the engine is now even playing at TCEC! Exciting stuff.

Today I'm glad to be releasing the first NNUE version of Heimdall, trained with self-play data. More information about the training process and the data used can be found in the README.

What changed

A fuckton, actually:

Of course, HCE is gone and has been replaced by NNUE. Top 20 here I come!

Pretty output support (thanks to @tsoj's patch)

Added MoveOverhead option

Significant refactoring of search limit handling (compound limits are now supported)

History LMR

Fix a bazillion bugs with datagen and add win/draw adjudication

Make isPV a static bool so that PV branches are specialized at compile time

Heimdall has a logo now, thanks @kan!

General refactoring to hopefully be more SMP-friendly, especially at TCEC conditions

MultiPV search no longer overrides the root moves provided with go searchmoves

There's probably more things I forgot to mention. It's been a lot of work!

Progtest

As is now customary, here follows a 1000-game progtest ran against the previous release (Pohl opening book)

Elo   | 366.03 +- 29.60 (95%)

Conf  | 5.0+0.05s Threads=1 Hash=16MB

Games | N: 1010 W: 848 L: 57 D: 105

Penta | [0, 1, 61, 94, 349]

https://chess.n9x.co/test/220/

This puts the estimated Elo of this release at ~3230 (although I think the actual Elo could be a bit higher)

Heimdall 1.0 download