Natch - Checking proof games

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Download Natch

Stable version (april 2020)
Windows 64 bits
Windows 32 bits

Beta version
There is currently no Beta version available.
iNatch latest version: 0.7
License: GPL v2.0
Content last updated: april 28th, 2020


Natch is a software solving a special kind of chess problems: proof games. It works on any Unix system (like GNU/Linux or Mac OS) and also on the Windows system in DOS mode.

iNatch is graphical interface for proof games which lets you use Natch. iNatch has it's own page.

Better than a lot of words, an example is a good way to show what Natch is able to do:

1st commendation, feenschach 1982
15+12. Position after the 23rd move
of White. How did the game go ?

The solution is:

1.e4 d5 2.e5 Kd7 3.e6+ Kc6 4.exf7 e5 5.h4 e4 6.h5 e3 7.Rh4 e2 8.Ra4 exf1=B 9.Qg4 Bc4 10.d3 d4 11.dxBc4 d3 12.Sf3 d2+ 13.Ke2 d1=R 14.Se1 Rd6 15.Bd2 Rg6 16.hxRg6 h5 17.Bb4 h4 18.Sc3 h3 19.Rd1 h2 20.Rd7 h1=S 21.Sd1 Sg3+ 22.fxSg3 Se7 23.Qe6#

This problem shows the Frolkin theme with a Rook, a Bishop and a Knight.

Natch solves this problem in few seconds:

These results do not mean that Natch is able to verify every problem. There are many kinds of positions where Natch needs days, if not weeks, to find a solution. But hopefully it may help SPG composers.

Stable version

The current stable version is 3.3 (april 2020).

Most users having a Windows system will probably prefer the ready to use distribution (as a DOS program). The default is a 64 bits version, but a 32 bits version is also available for older computers.

See the sidebar to download the files. The source files have been compiled successfully on Linux and Mac OS.

Beta version

There is currently no beta version available.

Please report any bugs in this version to