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Clover 4.0 - released. welcomes another strong chess engine!

Clover logo, source: GitHub

Clover 4.0 by Mr. Luc Metehau, is an open source chess engine released under the GNU GPL 3 license.

It was first released exactly 2 years ago - in 2021. Although it's a relatively young chess engine, it plays very well and is a viable competitor to other top ranked chess engines.

Source: MCERL (ongoing)

Here's what's new in the latest Clover 4.0:


After 2 months, new release is here. It comes with an improved search, but also improved neural network evaluation. Surprisingly, the arch is still the same, the major gain was switching from my trainer to CudAD.

Many, many thanks to @Luecx for creating such an amazing tool and I really recommend using it, as it has a lot of functionalities upon being able to train a new network.

Nevertheless, this should around 80-100-120 elo stronger than previous version (v3.3.1). I will continue using CudAD from now on, hence the version major change.


Source: GitHub

Let's see how Clover 4.0 plays.

We'll take a look at the game - a "thumbnail" performance of StockNemo 5.7.0 (white) and Clover 4.0 (black).

StockNemo is not an easy engine to beat; according to MCERL, it plays with 3104 Elo. The game in question will end after only 26 moves.


Classic King's Indian. How common a position type in this type of opening.

White takes a lot of liberties on the Queen's wing, Black looks for his chance on the King's wing.


Everything looks very good for both sides. The position is even.

Clover countered in his 11th move by playing Pawn on a5; thus preventing StockNemo's initiative from developing quickly.


A good move by white, aiming to prevent the position from being closed by playing black Pawn to the f4 square. StockNemo tries to "unload" this little tension in the center of the chessboard.


Novelty! And in what style :)

Clover provokes to play white Pawn on g4 assuming that in this way both his Knights will be attacked with a fork attack - which in prospect may lead to a loss of a piece.


StockNemo accepts the challenge.


The no-holds-barred ride in Clover's perforation is about to begin! Key factors for a successful attack on the white King will be the weakening of his position (no Pawn g2 and the removal of the white-square Bishop, who can act as an important defender.


After accepting the Knight sacrifice from the h5 square, black eliminates Bishop e2 a vital defender.


White's not the best 17th move is immediately exploited. Clover binds the ranks of the whites at the same time bringing a strong Bishop into play on g4.


StockNemo tries to activate its pieces by pulling them close to his King. Slightly better was 18.h6 which, as intended, could then lead to the use of the g5 square to block black's Queen from invading on h4.


Will the whites manage to occupy square g5 and stop the strongest black piece ?


No. Clover blocks access to the g5 square with its Rook.


Black achieves its stated goals. The idea is to create a real threat of a mate on the g2 square using Bishop f3 and the Queen.


A weak move in a situation where the game is getting out of hand for white. Taking away the black and irrelevant Rook is simply a waste of time in an already difficult position.


Black doesn't even force himself to take the Bishop on a5.

Clover reinforces his Bishop on f3, which is supposed to lead to the checkmate of the white King.


There are only 22 moves behind us in a game of really strong opponents, and already nothing can stop Clover from checkmate the white King.


Download ZIP • 3KB

I think Clover, is a chess engine with great potential. The talent of its Creator takes its power to a higher and higher level. Seeing his achievements in MCERL, I dare say that with this pace of development Clover will soon enter the top of the strongest chess engines.

Feel free to visit the download area.

Linux x64 – Compiled by Darius

Download 7Z • 19.51MB

Mac Apple Silicon & Intel – Compiled by Darius

Only in the Mac versions: sometimes Clover crashes during the game or exceeds the thinking time.

Download 7Z • 18.03MB
Download 7Z • 18.18MB

Windows x64 – Compiled by Darius

Download 7Z • 20.18MB


* Diagrams created in the ChessBase program.


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