I made a better icon for the game, if anyone wants it. It's the same logo, but in much higher resolution.
Now, the forum won't let me attach an .ico file, so here's the PNG. If you go to http://www.convertico.com/, you can convert it yourself easily without having to install anything.

EDIT:
This is completely unamazing, I have no idea why you even tried.

Not all that amazing, TBH. I just got tired of some of the really lo-res icons some of the GOG games come with, so I started making new ones for them. The GOG icon for Unreal Gold was only 32*32, this one, after conversion to .ico is 128*128.
If possible, I use the same motive, if I can find it in a higher resolution. Otherwise, I come up with something of my own. This one was easy. I've made a few by now. You'll find them in the relevant game threads.
I know that GOG also supplies hi-res icons, but those game box icons are much too detailed for the icon size I use on my desktop. I tried using them, but I can't see them properly. So I decided to start making my own, where necessary.

Nice! I was growing tired of the low res icon as well. New one looks a lot nicer on my desktop now.

That's me.

Thank you! I once made such icon for myself but can't replicate it for the life of me for some reason. Mine was way better but oh well, it's lost now. I sligtly edited that png of yours to have lot less green, also reduced saturation a little and used the site you proposed and it looks good, way better than the pixelated lowres garbage the game comes with.

PS: Im necroing this post because i've searched for UG icon and ended up here. So everyone else looking for such icon now will probably end here too. Especially as it was given away for free recently.

Actually, the "emblem" avatar from the game's goodies (attached) looks like it actually is a higher resolution and bit-depth version of the icon on the actual executable. I used GIMP to resize it to 256x256 (linear scaling) and exported it as a 24-bit PNG icon. It looks beautiful and faithful to the original icon.

UPDATE: I now have the icon uploaded on the PCGamingWiki Community site.

The colors are a bit on the more shiny side of things, but I personally think it looks more “gold”, as opposed to the yellow look of the original. It doesn’t have transparency, unlike the other ones posted here, but neither really did the original. I would have attempted transparency if it had a white background, but since it was black, and most people back in the day didn’t use black backgrounds, I decided to leave it square. If you want a circular one, go ahead and edit mine or use the source that I attached to the previous post. I wish I had a higher resolution lossless version to work with, but this will do for now.