Natch - Checking proof games


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 2.5 Beta (2009).

Yes, I know, this is called a beta version. But I never transformed this beta into the official release. This should have been done years ago. And now I have a new beta.

Most users having a Windows system will probably prefer the ready to use distribution (as a DOS program). It should work on Vista.

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

Beta version

The 3.0 beta1 version is available since september 2016.

Many improvements are in this version, which increased the speed of resolution. 2 bugs have also been corrected. Read the NEWS file to find out the details.

Please report any bugs in this version to