Rudim 3.0.5 - new version chess engine

 

Rudim - UCI-compliant chess engine written in Rust

Author: Vishnu Bhagyanath

Previous version: Rudim 2.1.3 participated in the qualifying rounds for the CEDR Chess Engine League, which features 64 of the best engines. The engine did not advance, but earned a spot guaranteeing entry into the qualifying rounds for the 6/2026 edition.

Rudim 3.0.5 what's new?

Network: v4-gen2

Features

• v4-gen2 network (f80ff39)
• check extensions (2b4f3a8)
• add_2_sub_2 (b2b71ba)
• decay history between iterations (b8945b5)
• history maluses (59abcdb, 833e322)
• promotion scoring adjustments (c61b8fb)
• native compilation / avx2 (17c751f, fc2430d)

Fixes

• none

Maintenance

• check two repetitions in search tree (a7f1382)
• gravity history & final alpha update (53d5964)
• refine null move pruning conditions (c1cb984)
• run CI tests in release mode (dcdd1e4)
• redo combine.sh script (3cfcd86)
• docs, chores (edd0e08, e8109fd, 8273987, 89a537b, 905b494, 73f2766, b530a30, 9dfec85)

Statistics

Node Count Reduction (Same-Depth Comparison):

Position	Depth	v3.0.4 (Previous)	v3.0.5 (Current)	Reduction
Starting	13	922.0k	1066.4k	0.86x
Advanced	16	3754.3k	23154.3k	0.16x
Kiwi Pete	12	920.1k	1357.2k	0.68x
Endgame	17	777.5k	5994.3k	0.13x

Tournament vs v3.0.4 @ 8+0.1 - for just this release, ran 2 smaller tournaments

x64 (AVX2 v3.0.5 vs 3.0.4)

Score of Rudim-3.0.5 vs Rudim-3.0.4: 366 - 191 - 443 [0.588]
...      Rudim-3.0.5 playing White: 197 - 92 - 211  [0.605] 500
...      Rudim-3.0.5 playing Black: 169 - 99 - 232  [0.570] 500
...      White vs Black: 296 - 261 - 443  [0.517] 1000
Elo difference: 61.4 +/- 16.1, LOS: 100.0 %, DrawRatio: 44.3 %
SPRT: llr 0 (0.0%), lbound -inf, ubound inf
1000 of 1000 games finished.

arm64 (NEON)

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Results of Rudim 3.0.5 vs Rudim 3.0.4 (8+0.1, NULL, 64MB, 8moves_v3.pgn):
Elo: 33.11 +/- 14.34, nElo: 50.05 +/- 21.53
LOS: 100.00 %, DrawRatio: 40.00 %, PairsRatio: 1.70
Games: 1000, Wins: 287, Losses: 192, Draws: 521, Points: 547.5 (54.75 %)
Ptnml(0-2): [17, 94, 200, 155, 34], WL/DD Ratio: 0.47
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Rudim 3.0.5 download