Hello, I'd like to submit my game to Gog (an old-school style cRPG). Does the game have to be complete before It's submitted? Or is it similar to Steam in that The game is submitted as a WIP and then released when it is ready?

Cheers.

GOG apparently allows in-dev games, but allow me to speak for the community now before you get a whole flood of possibly unfavorable repsonses that all of us would greatly appreciate if you finished the game before releasing it. You can submit by clicking on the "submit your game" button at the bottom of the screen.
Beware that the standards are much higher than Steam's, though. GOG has a curation system that's generally pretty difficult to get through.

WIP and the person above does NOT speak for the community but itself,ego.Good luck with the game.

No, I don't think the game needs to be complete before you can start the submission process. The upcoming tab is filled with games that have been accepted but aren't ready yet. It does help if you can show your work.
GOG also has an Early Access equivalent called In Development if that's the way you want to go, but that's not a necessary part of getting your game accepted while it is still unfinished and not as widely used as it is on Steam.

Here's the link to the submission form: https://www.gog.com/indie

Thanks for the responses. So I'm guessing I should wait until it's at least at a near complete stage. Currently only at around the %30 mark.