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Obsidian 10 - released

It's already the 10th version of this chess engine, and it hasn't been mentioned on Chessengeria yet…

Image generated by Darius using Microsoft Bing Image Creator

3648 Elo on the CCRL scale (1 CPU) is an amazing result for an engine that has been in development since April 2023, a mere 9 months! (as of January 2024)

Source: CCRL 2024-01-19

Obsidian is released as an open-source chess engine under the GNU GPL 3 license. Its author is gabe, who publishes his work on GitHub.

Although Obsidian in the current version uses and also in earlier versions used a neural network, considering that the first version debuted with 3003 Elo and today we have more than 600 Elo more, this must be impressive.

Here's what the author wrote for Obsidian's 10th edition.


This update brings quite large Elo gains, but also important bug fixes (such as taking a tiny amount of CPU while not searching). The neural network is the same, and the improvements are only about search and performance. Regarding usability, Obsidian finally supports being executed on hardware where pext is unavailable or slow (Ryzen 3...)

Elo difference:

Obsidian 10.0 vs Obsidian 9.0 (STC)
Elo   | 53.07 +- 6.69 (95%)
Conf  | 10.0+0.1s Threads=1 Hash=16MB
Games | N: 5008 W: 1588 L: 829 D: 2591
Penta | [6, 306, 1165, 977, 50]

Obsidian 10.0 vs Obsidian 9.0 (LTC)
Elo   | 56.96 +- 10.43 (95%)
Conf  | 40.0+0.4s Threads=1 Hash=64MB
Games | N: 2000 W: 630 L: 305 D: 1065
Penta | [1, 93, 496, 400, 10]


If, according to the author, the increase in strength of about 50 Elo at this level is due only to the fixes bugs, then I dread to think what strength Obsidian 11 will play with ;)

Just a few years ago, before the introduction of neural networks into the world of computer chess… If I had seen a chess engine starting at 3000 Elo and after less than a year having 3600 Elo on the counter, I would not have believed that this was the result of independent work.

However, on the day Obsidian 10 was released, that is January 2024, we are in a different era of computer chess. Today, the most powerful chess engines use neural networks and open their sources to the world.

And that's what open source is all about: sharing, developing, inspiring.

Which is most likely evidenced by the Obsidian chess engine right now :)

Heartfelt congratulations to gabe, whose chess engine ruthlessly broke into the top of the strongest!

So let's see how Obsidian 10 performs against opponents playing at the very high level.

Playing conditions same as in MCERL: 1 minute / game + 0.6 seconds / move

Platform: PC, Intel Core i5 (Haswell), Windows 10 Pro, Banksia GUI.

Game #1

White: Obsidian 10, MCERL: Elo not measured

Black: Viridithas 11, MCERL: 3537 Elo

Viridithas is one of the strongest chess engine written in the Rust language on the planet Earth.

It has played more than 2700 games in the MCERL cycle, confirming its class.

But even to it, such slip-ups happen...

Black's move.

An equal position in which white holds the initiative. Viridithas should first and foremost defend its King.


Better 34...Be4 and 35.Rfg4 Ree7= with equal chances.


White immediately seizes the opportunity to penetrate the eighth line, where the black King is.


Dear reader, in this position you can give chess mate in few moves!

Would you like to try to point out the first of these moves, leading to a forcing win?





If you managed to find this move, congratulations :)



Obsidian sacrifices the second Rook.


If 37...Kg6 then 38.Qf6#

38.Qf8+ Kh7

39. Qxg7#

Objectively looking at the course of this game, it was more this game that Viridithas lost than Obsidian won ;)

Nevertheless, a nice win, right?

Below this game prepared for download.

Obsidian-10_vs_Viridithas 11
Download ZIP • 1KB

Game #2

White: Obsidian 10, MCERL: Elo not measured

Black: RubiChess 20240112, MCERL: 3709 Elo

RubiChess, is an early 2024 fighter in the super heavyweight club. It is able to beat anyone, and has proven it thousands of times.

Black move.

RubiChess has built up an advantage on the Queen's wing. It activated the figures and boldly put Pawns forward.

Obsidian, on the other hand, has a strong point in the form of Pawn e6 and the potential for action on the King's wing.


Good move. Black takes the weak Pawn b3 with a parallel attack on the white Rook f1.



Obsidian decided that it was better to give up Rook for a strong black Bishop than to play a passive game with an advantageous opponent.

If 27.Rg1 then 27...bxa2 28.Qxa2 Bc4 29.Qb2 Qb5 with white probably losing.

Back to the game.



Several maneuvers that fit into the logic of the game of both sides follow. RubiChess wants to take the weak white Pawn b3, Obsidian meanwhile hopes to revive its forces.


29.Bb2 Nxb3

30.Bxd5 Nc5


Comparing the current situation on the chessboard to the situation that would arise after the preservation of the white Rook (27.Rg1), white is better off. They are playing freely on the white squares and, except for Knight, have managed to activate all the figures.


Blacks manifest their self-confidence. Slightly better was 31...Red8 with positioning of Black's Rook and enhanced action on the d-line.


Before the black Pawns on the wing begin to pose a serious threat, Obsidian activates its Knight.


Black self-confidence continued. Unfortunately for them, it was a weak move, after which black's advantage disappears. Probably RubiChess intends to press on the Queen's wing, when meanwhile the last two moves allow Obsidian to take a deadly initiative.



It was worth trying 33...Rcd8

The Blacks are playing as if they don't see what's happening on the opposite King's wing, or.... as if they didn't prove that the "freshman" Obsidian could do something to them ;)


White sacrifices Bishop b2, pushing for the enemy King's position.



The threat of checkmate on the g7 square appears. Black's position is impossible to defend.


If 35...Bf8 then 36.e7+ Kh8 37.exf8Q+ Rxf8 38.Qg7#



A hopeless situation. As a result of overestimating their own capabilities and making wrong decisions early on, black can only watch. The finale of this skirmish is approaching.



At the price of a Rook, black “momentarily” dismisses the moment of defeat.

38.Rxc1 Qe5

39.Qg6 Qxd5+

40.e4 Qxe4+


In a few moves the black King will be checkmated.


42.Rxc4 Bc5

43.Nf6+ Kxg7

44.Nxe8+ Kf8

45.Qg6 Ke7

46.Qf7+ Kd8


Bravo Obsidian!

It found itself in a difficult situation against a strong computer player from the top, did not lose its resonance and won nicely.

Below this game prepared for download.

Obsidian-10_vs_RubiChess 20240112
Download ZIP • 1KB

It plays well, this "newcomer" Obsidian 10.

Too bad it won't play for all chess engine enthusiasts. Unfortunately, the source code is written in such a way that it does not support compilation of this engine for Macs with Apple Silicon and Intel CPUs. Compilation for machines using Linux and ARM CPUs was also a failure. I have not found on the Internet a compilation of this engine for devices using Android.

Nowadays, there are fewer and fewer chess engines that are only written for one or two operating systems. Typically, authors are keen to make their work available to the widest possible audience.

This is also the mission of the Chessengeria blog, to promote, popularize and disseminate computer chess.

I hope that in future versions of his excellent Obsidian, gabe will enable to use his engine not only on the Windows platform but also on Android, Linux, and Mac :)

I encourage you to download and check out the Obsidian chess engine.

Linux x64 – Compiled by Darius

Download 7Z • 1.71MB

Mac Intel x64 – Compiled by Darius

Download 7Z • 1.60MB

Unfortunately, I have not been able to compile a newer version of Obsidian than Obsidian 7 for Macs with Intel CPUs.

Windows x64 – Compiled by Darius

Download 7Z • 1.40MB


* Diagrams created in the ChessX.


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