Not really. Going from Mobile back to PC is very very easy (PC to Mobile is another story). If your game already works on mobile, it will 99.9% work on PC. The amount of platform specific Unity bugs is actually quite small, in my experience. Especially with 2D games that aren't using crazy shaders (in my experience, most of the platform specific bugs are GPU shader crashes, especially on Android. And again, that's only on Android. PC has far less buggy GPU drivers than Android).

You might need to adjust some screens so they work better with a mouse instead of with taps, but this game doesn't use multi-touch or anything that can't be done with a mouse so I don't see an issue with that.

You also need to write platform specific IAP and notification code, but again, going to desktop you won't have notifications, and writing platform specific IAP code is not that big of a deal, especially compared to porting your entire game.

Short story is, these guys chose their engine very poorly. They had already experienced cross platform issues in the past, and seems like they just decided to ignore them until it was too late.

I have no sympathy.

I found a bug in Unity which happens on Linux on XFS partitions larger than 1 TB. Such kind of bugs are clearly system specific and hard to debug / support unless you have that configuration set up. Responsible developers take obligation to support their product. If someone intends to produce something and forget about their users - that's close to garbage.

In my case I bought one game and was hit by this bug. I contacted developers with strace data and got no response. Then I contacted Unity developers and they actually got back to me and confirmed that it's indeed the case with large XFS partitions (they had to set up that test case to verify it). They produced a custom build of Unity player of the same version with patch backported, and I was able to run the game.

Now, those game developers obviously don't care about supporting such cases, yet they sell the Linux version. I don't appreciate it on one hand, on the other hand may be it's better than not having that version at all. But I can see a point of some being exhausted and trying to avoid bug reports for systems that they can't properly support.

That's unfortunate that the game developers did not get back to you. They should have at least given you a response. There is no excuse for that.

The proper response from a Unity game developer who wants to sell a Linux version but not support it is pretty simple- just offer refunds for anyone who has problems. 0 work and problem solved.

Also, good Unity developers know there are platform specific issues (and how to solve them). I'm not saying platform specific bugs don't exist. They're just rare. When they happen, post on the Unity forums or Unity Answers site. Unity employees will read it, and get back to you. The support is great. This is why you use Unity. Let Unity do this work for you!