I've started reorganizing my desktop and in the process I created five hires icons for
Abe's Exodus
Abe's Oddysee
Giants
Painkiller
Screamer
Unreal
Unreal 2
They aren't perfect but they're a nice change from the standard GoG boxshot icons. Feel free to add to the collection, a screenshot of these five is attached.
Edit: Added icons for Unreal 1 & 2, updated preview image

It's slightly mad how big icons are getting. Nice ones though, they made from the desktop wallpapers?
Also, is that a futurama desktop?

Mostly... Abe's Oddysee has thee sign moved up so that the image is more square and a bit of contrast enhancement on the text
Abe's Exodus is a blown-up, contrast enhanced, partially transparent variant of the wallpaper
Giants is one of the artwork images combined with the logo from one of the wallpapers
Painkiller is pretty much a cut out variant of the wallpaper
and finally Screamer is a heavily edited screenshot I made.
Edit, yes that's Futurama... actually not a wallpaper, but a warpsharped image from movie #2

...i don't have vista. are icons that big on it?

Not by default, you can change the icon size with Ctrl+Mousewheel on the desktop from anywhere between 16x16 to 256x256.
Edit Here's a screenshot with a much smaller icon size

Updated with icons for Unreal 1 & 2