Steam version "Rain world" was updated 6 april. Today 18 april and GOG had still nothing. GOG whats wrong with you?

Usually patches come a little slower here. Most of the time it's the developer's fault. Maybe ask them whether they submitted the patch to GOG.

They did sent it, but it got misflagged as a QA file so they sent it again last friday. It'll probably be uploaded sometime this week.

http://steamcommunity.com/app/312520/discussions/0/135513549099064253/

This is from the Steam forums, April 11th:
"@ Jonathan66100 : Soon my friend! The PS4 team had to track down some additional crashing errors, but those should be sorted now. That patch is through QA and has been submitted to Sony cert, so it should be out pretty soon. For those who are on GOG, the patch will be live this week, thanks for your patience!

In related news we'll have a slight tweak patch, v1.015, coming to all platforms this week, which fixes the map discovery bug as well as make vulture masks droppable rather than throwable again. We've tried to set it up so that all platforms get it simultaneously this time, so fingers crossed!"

As patches also need work and QA from GOG, maybe they decided to wait for v1.015 instead, but it's taking more time than they thought it would... as it's not out yet. Just read this thread here. To disproof my alternative theory.

Thank you all

Version 1.015 went up today on GOG. In addition to fixes, it should be a bit easier now for those who were having trouble getting started; more food, lower karma gate requirements and you won't lose karma for quitting if you do so within 30 seconds after a sleep cycle.