Reviewers have commented that the game is out of date on GOG.

Is this still true?

Is it a better version available on Steam?

I'd like to know too.
The discounted price is cheap, but if the title has been abandoned here, I'm not going to bother.
Can someone who also uses Steam ask the dev to update his game?

The GoG version is 2.0.9 and does not have multiplayer or online features like weekly challenges.

The Steam version is 3.1.3 and has all those online features, but it's much more expensive.