I got a little idea.

Take a game like Worms W.M.D - There is no PC DRM Free physical release.

What if I took Worms W.M.D box with steam, throw the useless DRM CD into garbage, then took my own CD, printed the game art on it, then burn GoG installer on the CD. This way I have some kind of substitute for the official physical relase.

What do you think of it?
Would this be legal as long as I won't be selling it?

Well, who wants to break it to him gently?

:)

Uh, yes, you can. As long as it's intended for your personal usage, that is.

On the contrary. You can do whatever you want with your gog installer. You can burn it on a DVD and put it in any box you want. You just shouldn´t try to sell it :)
We also have a rather big collection of fan made covers for your DVD-cases here: http://www.gogcovers.com/index.php?title=Main_Page

EDIT: My joke was aimed at the fact, that other people had this idea looong ago.

Oh you sweet summer child.

It's DRM free. You can do whatever the fuck you want with it, as long as you don't sell or distribute it to others.

So what was that "who wants to break it to him" part?

I toldya it's not for selling.

My joke was aimed at the fact, that other people had this idea long ago. Sorry :)
FYI, you can use this thread for urgent requests and such: https://www.gog.com/forum/general/unofficial_dvd_covers_for_gog_com_games