Because releasing on another store (much more so on a store with special requirements - like GOG), always means more (paper-)work for you.

And at some point, you have to decide, whether those max. 8% to 12% possible (not granted!) more revenue are worth that extra hassle.

Add to that the fact, that there exist half a dozen "GOG-lookalike" sites on the internet, where all the games on GOG can be downloaded for free or against 'a voluntary donation'...and it's really not that hard to understand, why some developer/publisher may come to the conclusion, that they should rather stay away from GOG.

There are as well "free" Steam-alike sites. So i am afraid, this is not a "GOG exclusive".

Sure, there might be some trojans inside. but free is free, never look a gift horse in the mouth, they say.

Anyway, i am still sad they did not release this Metroidvania there; although this is even more of a reason supporting those other Metroidvanias actually available here, in a pretty crowded genre.

No GOG no buy... because i can barely play all the other Metroidvanias anyway...

Wasn't aware of this title as well, looks nice. I voted on the related wishlist entries I hadn't seen before. Better communication overall would be a great thing, but how big of a chance of that happening is another story maybe.

1. It is more work to release the game on several platforms (e.g. if it is a very small studio).

2. Related to above, they might not believe they get enough extra money from the other platform(s) for the extra work involved.

3. The game might rely so heavily on certain features of certain platform that they are unsure how feasible it is to try to release it on the other.

4. They might prefer to have some kind of DRM (albeit maybe not so much on an indie game).

People keep saying things like that, but considering how many devs do manage to release their games here and on Steam and keep them up to date on both platforms even with frequent updates, and yes even small studios and even one man developers, I find that hard to believe. It can't really be that much more work if others can do it so easily and with no problems.

The reality appears different for everyone, so a lot of things can be seen as an obstacle and dependable on individual resilience there is in many cases no sufficient acceptance in the end.

Different studios perceive it differently. Some consider it too much work for the potential extra money, others not.

It is a similar discussion like why don't all digital game stores support Linux? It could also be seen to be just added income, but many don't consider it worth the extra effort, stores like GOG, EGS and EA which mostly or only support Windows.

Then there is the vaporish site which strongly supports Linux, but I presume they have other reasons for it than thinking it will now bring them lots of extra income. It is their plan B in case Microsoft locks down Windows and makes their life too uncomfortable in the long run.