I don't know if someone intresting in that but i want share what i have . the forumsearch has no match to ufo enemy unknown.

http://www.mediafire.com/?gb9djzbnvbn7oo2

well following the readme from inside the package:

So here we have the long lost pre-release demo for UFO: Enemy Unknown.

Found this in a badly mangled state on an old PC Format cover CD (Gold '95) - it was
in a ZIP archive together with a demo for Dragon Sphere, but with no folder structure.

This would actually be my first ever copy of UFO, but I was never able to play it.
Just recently I decided to take a closer look, and was surprised no end to find out
what it actually was.

So! By hunting through the executable and comparing the file names to those from the
final release of the game, I've rebuilt the folder structure and got it running. The
sound settings are configured for use with DOSBox.

The demo announces itself as being made for PC Gamer, so I'd assume it originally came
from one of their cover discs - though whether it was broken there too, I wouldn't know.

When you run the demo, you'll first be shown some old screen shots, then the soldier
inventory screen. There's no "OK" button in this version, so you'll need to right-click
to clear it and start the actual game.

"Trigger" scroll mode is active by default, you'll probably want to use the options
screen (click the "?" icon) to switch to "auto" mode and turn the game speeds down.

Many of the items hidden in this demo appear different to those from the final release
of the game, but you're only granted "vanilla" equipment by default. If you want to see
and use all the other stuff, move the files from the EXTRA folder into the MISSDAT
folder (overwriting the previous versions). This'll fill your SkyRanger with junk and
grant one of the soldiers some psi skill.

That pretty much covers it. Have fun!

Nice find!
On In'side Multimedia 7/94, I found a German demo of the game, dated to May 27, 1994. Your demo is from February 25, 1994.
I noticed that some of the files in my demo are older than files in your demo. For example the MISSDAT files are about 5 days older.
http://www63.zippyshare.com/v/15453723/file.html

Also: Is this the the DragonSphere demo, that you mentioned? I found it on In'side Multimedia 5/94.
http://www63.zippyshare.com/v/27007219/file.html

It's possible that this the DragonSphere Demo is.
Btw thx for the German UFO Demo.

Is this also some kind of beta demo?

Actually, there exists a version with the original folder structure intact:
http://cd.textfiles.com/sprintos6/GAMEDEMO/LZ/UFO.ZIP