To answer the question about why this mod is being promoted as DLC, it's because Revision is officially sanctioned by Square Enix. Caustic Creative went through the process of having the mod legally cleared for distribution. There were issues like textures that had to be replaced for copyright and also an effort made to tie Deus Ex in with the prequels by adding lore text that references events and entities from Human Revolution.

As for what the mod does, it's basically a map pack for the campaign missions. Some maps are complete reworks from the ground up while others are essentially the same as the originals but with added props. It also integrates the Human Renovation, Shifter, and Biomod mods. Note that you can't play with the vanilla mechanics, you have to choose one of those mods to play Revision (Human Renovation is default and treated as "vanilla"). The mod also comes with an optional alternate musical score which is more ambient, like the prequels.

Can i use this mod with a French (txt only) or any non English version of Deus Ex ?

I absolutely agree with you. As a company famous for consistently touting DRM-free principles they have become suspiciously fond of non-customer-friendly sales tactics.

http://www.moddb.com/mods/gmdx
Reworked AI, gameplay changes, perks, no more ammo hoarding etc.
Too much to write.

Yes, a lot.
gog advertise galaxy as optional, when lately their patches (aka full re-DLs because they decided we don't deserve proper patches unless using galaxy...) shows that it isn't optional.
This, if as their store page states, confirms that it isn't.

What a strange attempt at justifying the 'GOG installation of Deus Ex: GOTY' minimum requirement.

Does anyone know if these games run on dosbox or some form of dos?

So, are we going to see such mod releases for other old games?

Pussycats 250

A question for people who have played both vanilla and modded. Which one would you recommend for a first time player.

I sort of lose all my gamer street cred when I talk about this game. Bought it on release (huge fan of System Shock and loved the idea of the setting / story) and... never really got into it.

Tried it a few years later and never got that far then either - but at least spent more time with it than I initially did. I know, I know right? One of the classics of all time with a story I REALLY want to experience and it just never works for me.

Maybe this mod will give me the excuse to try it one more time...

I think I was turned off by trying to play the opening "less like a shooter" when maybe that's the way to go before I get a few points and mods to make other playstyles more feasible. In the very least, I'm sure I should care less about how I play the opening and just worry about getting through it so I can get into the later parts of the game.

Either you are drunk, or because I just woke up from a long nap, I am still half asleep (mind).
This doesn't make any sense to me.
Why would GOG, or anyone, give you access for free to an upgrade of the game they are selling, if you do not even have the game that is required, bought from them in the first place?
Because you are a nice guy?
The original game was a full on Windows game, so I seriously doubt it is now a game that requires DOS or Dosbox.

I'd think he could just download the mod from the site of the mod makers, no? Or is this a wholly GoG exclusive mod? Or is it only distributed through storefronts because it's an officially sanctioned mod?

Given that you can download a standalone installer for it, my guess is that you only need Galaxy if you want the achievements.