what is the history of the software company astralsoft ? 
In 1987 This company released a famous computer game called "XOR" - the ultimate
maze challenge. 
I have already googled myself, and found a XOR "memorial web site"
www.danceswithferrets.org/xor but I did not find out who or how many
persons were behind this company or when and why they went out of
business. Did they release any other games or software?

(I am not talking about the Russian software company here.)

Xor was initially created by Astral Software and published by Atari in
1987. The game was later rewritten as Prospector in the Mazes of Xor
for the Commodore 64 and republished by Logotron.
http://www.angusm.demon.co.uk/AGDB/DBM1/PitMoX.html

Logotron published at least six games for the Commodore 64 and one for
the PC. http://www.gamefaqs.com/features/company/73262.html

That company is still around, now specializing in educational software.
http://www.logo.com/


Astral Software went on to develop three more titles.
http://www.atari.st/list.php?developer=213&action=developer
http://www.mobygames.com/browse/games/o,100/j,665/

Unfortunately, according to at least one website, Astral is now defuct.
http://www.the-underdogs.org/company.php?id=38

I hope that helps.
Brian