Let me reply to you point by point, taking Carmageddon: Max Pack as the game being discussed. See my post above for the comparison between GOG files and Steam files of said game.
how about not having internet in the computer you are installing?
No problem, copy paste the game and you play.
how about all the processes a game installation does?
Carmageddon doesn't have them. Games that do need them contain the info in installscript.vdf, in a human readable format.
how can you install a game without an installation setup?
Unzip and/or copy the folder
how about registry keys created during setup?
Installscript.vdf contains them, if they are needed
how about icons and start menu shortcut entries?
Right click on exe, send to desktop. Copy said shortcut to start menu if wanted.
Bit more complicated with DOSBox games, but I think a script or two should already exist for that.
how about DLL files needed and copied outside of the games directory?
Part of dependencies, see installscript.vdf again
how about third party software needed to run the game?
See folder redists for any needed redistributables
how about having a way to check the integrity of the installation and files?
Zip it. Archives do have a self check, or you can keep an md5/sha1 hash list somewhere. Whatever works for you
how about archiving/backing-up the game in a organized way?
Archive with program of your choice, organize them according to taste
how about the garanty the version will remain this way, drm-free?
None. If you do keep the files backed up though, those don't need steam, and won't be revoked. Similar to Imperial Glory Mac edition from GOG
how about patching the game?
Steam required to download patch. Copy files to offline computer, play (assuming game remains DRM-Free of course)
how about official information from the seller informing the consumer what she/he is buying?
1 license to the game Carmageddon: Max Pack. Additional software may be required.
how about making games installation a thing about you and the game and not involving third parties?
Innosetup is a third party. Nullsoft is a third party. MSI install scripts are a third party. Archivers are a third party.
Copy pasting the game though isn't.
how about supporting alternative ways to install a game besides restrict client based ones like steam?
Copy pasting the files?
and how about supporting competition and not letting steam become a monopoly?
Take your pick. Origin, UPlay, GMG, GG, DotEmu, GOG, GetGamesGo, Fireflower Games etc. All have both DRM and DRM free games.
this is what GOG has
GOG Galaxy doesn't. Linux games come (also) as archives, not installers. Are those not DRM-Free, even though the exact same files are provided to you?
this is what DotEmu has
Haven't used DotEmu, no idea
this is what HumbleBundle has
HumbleBundle offers quite a bit of games as archives, not installers. Are said games not DRM-Free?
this is what steam doesn't have
Yes, Steam skips the installation part of Deliver/Install/Play. Delivery is DRM'd, Play may be DRM'd or DRM-Free.
also i find it troublesome steam supporters using GOG, GOGs servers, GOG bandwith, GOG forums to promote games from a competing system,
knowing that some games they advertise here are also sold in GOG so potentionly damaging GOGs sales.
so my question is doesn't steam have their own forum system which the steam supporters can carry on this?
unless steam forums would censor and ban this king of information? is that the case?
but credit to GOG for the freedom of speech we have here
and it also proves GOG forums are a safe place for gamers to come and discuss anything with freedom and no fear of being banned
That is exactly the reason we discuss it here. Because people want to discuss it, and because we can discuss it.
and i hope, no matter how many pages this thread has, there always will be GOG supporters that will challenge the argument steam can even be DRM-Free
And I hope at least a few of them will question what is DRM after reading this thread, and not blindingly go with a very strict definition. People have different definitions of DRM. Some require all 3 of the Deliver/Install/Play to be DRM-Free, others require only the Play part to be DRM-Free, some want both the Install and Play to be DRM-Free.
pss: double irony; in the GOG forum, a GOG costumer defending GOG is down rated!?!? isn't something wrong?
I've said it before, I'll say it again. What most Goglodytes don't tolerate is intolerance. Feel free to discuss and debate, but do have arguments. Don't just go "Your argument is false because I say so". Explain your reasoning. It may be different from others, but proper discussion is always encouraged.