flyme_tothemoon: Redout Steam version has multiplayer, GOG doesn't.
https://www.gog.com/forum/general/release_redout_solar_challenge_edition_72e22/post58 "Buy our game now and maybe we'll add multiplayer later"
zlep: Well... "Buy our game now for half the price you'd pay for the same content on Steam (minus multiplayer). Maybe we'll add multiplayer later."
Personally, I wish all devs who released multiplayer-less on GOG were as cruel...
They even explain this a few posts later in the same thread:
"LAN multiplayer is not possible at this time as the current implementation still needs the Steam apis to function. I know it's dumb, but that's the situation :( "
So it seems as if they developed the game using the Steam API and they know it would require additional work (time and money) to even be able to have in on GOG as well. The y knew it would be unfair so they decided to cut down the price and they were open about it. I really don't know if we are treated as second class citizens here - I don't feel this way but sometimes you'll have to add the positive and negative things to see if the end result is positive or not.