I totally agree that GOG and game developers should provide game updates to their customers.

But many game "updates" are not really better.
For example:

1. King's Quest IV: The Perils of Rosella
- This game have many different versions, and some original features are dropped from newer versions
- [url=https://tcrf.net/King%27s_Quest_IV:_The_Perils_of_Rosella#Revision_Differences]https://tcrf.net/King%27s_Quest_IV:_The_Perils_of_Rosella#Revision_Differences[/url]

2. Loom
- Some original features and content are missing in newer versions
- https://www.movie-censorship.com/report.php?ID=802320

Modern video games often get "updates" from upsteam developers, but those changes are not always good. Newly introduced bugs aside, some "updates" just make the game worse.

Happened with GTA 3 San Andreas on Steam. I remember reading that is was like a downgrade to the console version.
https://www.pcgamer.com/grand-theft-auto-san-andreas-steam-update-removes-songs-resolution-options/
It's my biggest gripe with steam, that it doesn't allow you to play out of date games.

There was botched patch 1.0.0.6 for S.T.A.L.K.E.R.: Shadow of Chernobyl. It introduced some very buggy recurring side quest in the Wild Territory and I think it broke something related to multiplayer. They rolled back to version 1.0.0.5 on Steam. I never played the GOG version but some other GOGer claimed that it's version 1.0.0.6 on here (but that was years ago and it may have been changed since then).

Edit: Okay, found this article:
[url=https://pcgamingwiki.com/wiki/S.T.A.L.K.E.R.:_Shadow_of_Chernobyl#Essential_improvements]https://pcgamingwiki.com/wiki/S.T.A.L.K.E.R.:_Shadow_of_Chernobyl#Essential_improvements[/url]

I was partially right, the patch breaks stuff in singleplayer but it's actually recommended for multiplayer. The article also links to downgrade instructions for the GOG release on the S.T.A.L.K.E.R. subforum.

Edit 2: GOD DAMMIT. The forums won't get the link correctly because of the colon. Screw it, removing the link, leaving the URL as text.

Edit 3: GAAAAAAAH. The forum apparently automatically turns URLs into links. Screw it even harder, I'm outta here.

Duke Nukem Anniversary

I don't think "fucking dumpster fire" even comes close to beginning to accurately describe this colossal piece of shit. :D

Flashback 2013

D/Generation HD

Agreed, I was a little bit pissed off to discover, when I bought the Police Quest series on gog, that the first game was the later point and click version. Perhaps it's just the nostalgia talking, but those old parser games had and still have a certain inescapable charm.

GOG has added the EGA version some time ago (probably years ago). When you run the game now, it asks you if you want to play the VGA or EGA version.

Oh? That's awesome to hear thanks :) I made a post back in 2012 asking about it, and at least back then it looked like it was only the vga version.

King's Quest 5:

Originally released on floppies with all dialogue as text, a while later they released a talkie version on CD. Apart from the voice acting being incredibly awful, the talkie version removed the dialogue text so it was impossible to play it without the speech.
Unfortunately, GOG only has the talkie version of 5 which makes the game very difficult to play for anyone with a hearing impairment and pretty hard to play for anyone with good hearing.

GTA series: Some titles from the soundtracks removed. Also, no hot coffee any more in Sand Andreas ;)

Far Cry 1: AI can look through tents in the latest version.

Panzer General 2: The tank T-34/41 didn't cost anything in the first version afaik :P

What games change the AI stats in updates to let the players win more easily?

More than half of ports and "remasters".

Indeed. Although not sold by GOG, the UE3 based Bioshock 1-2 "Remasters" are 100x more buggy than the UE2 originals and introduced everything from game-breaking bugs to random save-game corruption. Originals got "Very Positive" on Steam reviews, the new ones are Negative/Mixed for a reason. If these two games ever do come to GOG, then I hope GOG put their foot down and require the originals be included DRM-Free with the "remasters".

I'd say Monkey Island 1 for me. We had the VGA (which had the all the audio and the MI2 style hud.) But I prefered the older version with the text hud (which changed colour when you got to LeChuck's cave!) and the big blue arrows. We also have the current version on GOG which is just alot worse than the VGA version.

I'm still waiting for an opportunity to play the non-redux Metro 2033 and its apparently darker, superior atmosphere.

I have the original retail Doom 3, though.

And the AvP with its original, bearable, actor on the first level's wall monitors. Immersion is so broken by the terrible overacting dude in gog's edition.