Steam version just got updated to v2.0, here's changelog:
- updated to Unity 5
- various engine optimizations
- improved mime puzzle
- miscellaneous bug fixes

How is then GOG's version supposed to be v2.1.0.3?

These are their installer versions, mostly unconnected to the developes' versioning.
Mostly, haha! :-D

Is this 2.1.0.3 version that's available for download here at GOG that new updated version?

I'm pretty sure it's not. Hope they'll still roll this out. But then again, why wouldn't they...

Nope, GOG version is at least few months old.

This is really nice, I didn't expect them to update this at all.

Me neither - I just surfed around a bit to check out their sites and some of them are just plain abandoned. http://postudios.tumblr.com/ last update over a year ago. I would have expected them to announce something like an update to GK. Love this game.

They said on Twitter that they'll be releasing the GOG version "later today". :) https://twitter.com/POStudios/status/740551688822607872

I have to say that I kinda like the old version better.
Differences are not that big though, there's screenshot in attachment for comparison.

Uh, GOG still has only the old version up, right?

There's another tweet on the sitch though: https://twitter.com/POStudios/status/740632228133277697

By now I'm really starting to wonder what's taking so long. Phoenix Online Studios sent the update over a day ago. You'd think that would be enough time for GOG.

I wouldn't worry too much. They probably have their hands full with summer sale and stress test currently going on.
On top of that, GK is amongst free game awards during the sale.

There's a new Patch 2.01 listed in downloads.

The installer also has a new version 2.2.0.4.

Since they never released version 2, the patch is completely superfluous and everyone has to download the complete installer anyway. But who cares, what's important is that the new game is here at last. :) Starting my download right now. :)

Edit: Oh wait, the patch is 1,2 GB so it should cover the engine switch and everything after all. Never mind. :D Regardless, it's almost the same size, so....

Could it be possible to run this version or the previous one in a laptop with Core I5 8GB Ram and Intel HD 4000?