There's a lot of great freeware games out there and it'd be pretty cool if GOG could bring more of them to its catalog. Which games do you think would be a good fit here? Try to keep it to one entry per post and make sure to link to the wishlist. It couldn't hurt to include gameplay footage or anything else you feel may be informative.

Bungie's 1994 first person shooter is now freeware. It was a Mac exclusive but now can run on Windows and Linux too with the help of Aleph One.

Marathon
>Gameplay
>MobyGames
>Original Game Files From Bungie
>Aleph One Versions for Windows, Mac and Linux

Abuse: https://www.mobygames.com/game/dos/abuse

Traffic department 2192
https://www.gog.com/wishlist/games/traffic_department_2192

Great(and very mature for the time) story with strongly written characters, game is a fun overhead vehicle shooter (helicopter levels are a bit to get used to).

Game was made available for free in 2007

Marathon 2: Durandal
>Gameplay
>MobyGames
>Original Game Files From Bungie
>Aleph One Versions for Windows, Mac and Linux

I'll go with the wishlist, so #1 would be Starcraft + Brood Wars. Free on Battle.net but not actually freeware, right?

https://www.gog.com/wishlist/games#search=starcra&order=votes_total

Maybe GOG could do a Betheda offer - "buy Diablo or Warcraft 1+2 bundle, get Starcraft + Brood Wars added to your account!"

Lost Vikings 1+2 are also high on the wishlist, something similar could be done with them.

https://www.gog.com/wishlist/games#search=lost%20vik&order=votes_total

Then there are others like One Must Fall 2097, SimCity 1, Dreamweb, the already-mentioned Abuse, Halloween Harry, etc.

I'm glad we've been getting some freebies like Postal 1 and now Mike Singleton games, but I'd still like GOG to support highly-desired freeware titles.

Marathon Infinity
>Gameplay
>MobyGames
>Original Game Files From Bungie
>Aleph One Versions for Windows, Mac and Linux

White Chamber - really good puzzle/adventure game with horror elements and nice music. Can't stop myself playing it from start to finish. That is very rare, especially for an adventure game where you have to "think" what items you can use and on what.
http://www.studiotrophis.com/site/downloads

Remake is in the works for several years now...
http://thewhitechamber.lockeddoorpuzzle.com

Princess Remedy In A World Of Hurt
>Trailer
>Steam
>Gameplay
>Download

I'm sure I put it in similar threads before, will just add it again:
The Spirit Engine 2 | wishlist entry | MobyGames
(can add the first too if you want)

The short adventure from the guys who made Scratches and develop Asylum, currently.

All the PS1 demo discs but why would they put them for free when they could make money off them like The Suffering.

Also just re-adding:
Heroine's Quest: The Herald of Ragnarok | wishlist entry | MobyGames

Path Of Exile

Well, with One Must Fall 2097 already mentioned and the status of Dynamix Metaltech games a bit unclear, I'd go with Xargon.

Dungeon Master series, but I'd pay for it.