New engine releases & news H1 2026

[ranzuh]

I have released new version of Ratsu. This release brings tuned evaluation weights and late move reductions to Ratsu. Testing against Blunder v5 and Stash v14 suggest that Ratsu 1.1.0 would land at around ~2023 Elo CCRL.

https://github.com/ranzuh/ratsu/releases/tag/v1.1.0

- Eetu

[Gabor Szots]

Eleanor 4.1 (bugfix for 4.0)

https://github.com/rektdie/Eleanor/releases/tag/v4.1

[ZlomenyMesic]

Kreveta 2.3.0

https://github.com/ZlomenyMesic/Kreveta ... tag/v2.3.0

[CMCanavessi]

Most important release so far!! Huge update that brings more than 400 elo over previous 1.3! It's now well over 2300 elo (I got around 2330). Looking forward to the CCRL testing with this one
Engine has better search, better evaluation, better use of the TT and on top of that, it's way faster. Time management has also been tweaked and I'm very happy with it.
There's also now a "bench" command that you can use, with some options like "bench verbose" or "bench depth 13" (default is 15) or just "bench 13", you get the idea.


Facón 1.4 - Hoja
https://github.com/CMCanavessi/facon/releases/tag/v1.4

+430 Elo over 1.3 (Ordo ~2330, gauntlet 1040 games at 2min+1sec). NPS: +53% (Linux), +92% (Windows).

Search
Check extension: when in check, extend search depth by 1. Check evasions are now resolved at full depth instead of dropping into quiescence. +30 Elo.
Static Exchange Evaluation (SEE): full exchange simulation with x-ray discovery. Losing captures pruned in quiescence search. Shortcut: skip SEE for captures where the victim is worth >= the attacker.
Reverse futility pruning: at depth 1-3, if the static evaluation already exceeds beta by a margin, prune the node without searching. Like NMP without the null search cost.
Move-level futility pruning: at depth 1-2, skip quiet moves when the static evaluation plus a margin is still below alpha.
Make/unmake legality: the per-move board copy in is_legal() (~700 bytes per pseudo-legal move) replaced with make, check, unmake. NPS: +130%.
Move scores computed once: parallel scoring array eliminates O(n^2) move_score() calls during selection sort. NPS: +9%.
LMR table precalculated: startup-initialized LMR_table[MAX_PLY][MAX_MOVES] replaces per-node log() calls.
Quiet queen promotions in qsearch: pawn pushing to the 8th rank without capturing is now visible to quiescence search.
Forced move instant-play: only one legal move = play immediately with zero search time.

Evaluation
Piece mobility: pseudo-legal squares per piece, excluding own pieces and enemy pawn attacks. Knight 4cp, bishop 5cp, rook 2cp, queen 1cp per square.
Open/semi-open files: rook bonuses for files with no pawns (+20cp) or no friendly pawns (+10cp).
Rook on 7th rank: +20cp bonus.
Bishop pair: +30cp when both bishops present.
Knight outposts: +20cp for knights on ranks 4-6 that cannot be attacked by enemy pawns.

Transposition Table
Depth-preferred replacement: shallow entries for different positions no longer evict deeper entries.
TTEntry::depth int8_t to uint8_t: fixes overflow at MAX_PLY (128).

Time Management
Base time budget increased (MOVES_TO_GO 30 to 25).
Progressive easy-move reduction (x0.95 per stable iteration, cumulative, cancellable).
AW fail-high time extension (proportional to fail-high count, capped at x1.50).
Time cap relaxed (remaining/3 to remaining*2/5).
Mate reduction only when winning (no longer triggers when being mated).
TM extensions now always run before checking soft_stop().
go depth X without clock no longer activates TM.
movestogo UCI parameter now parsed and used.

Infrastructure
bench command: 10 positions, depth 15 default. Quiet by default, bench verbose for full output.
FACON_DEBUG build mode: diagnostic counters compiled only with -DFACON_DEBUG=ON.

Checksums (SHA1)
09f0fba11511470f8b06102a8f118293ef94fe4e facon-1.4
a8815dbc6e952bceee4f5f7c7478f96eb3c7c18b facon-1.4.exe

https://github.com/CMCanavessi/facon