Why not? Are you just philosophically opposed to Unity?

I was going to ask you this for Ticket to Earth, but it would seem weird to ask, given that I can't get that game working myself (not because it's Unity, but because a large percentage of Windows games just don't work on my Wine setup). I have lots of games (didn't really count; at least over 100, maybe 2-300) that use Unity. Some of the best games I own use Unity. While I would never use Unity myself in a game project (or Godot, or any other engine tied to a scripting language), I don't see a technical reason why Unity wouldn't work for you in general.

Oh, to answer your question: it does, indeed use Unity. I can't answer the demo question; there may well be one on some other site (but not on gog). If you want an older version of the game, you'll have to contact support. You may or may not get it. It's not automatic. You could also just get a refund if the game doesn't work for you.

> Are you just philosophically opposed to Unity?

In this case, would I ask for a demo version or
an older version of the game?

>Why not?

Only very rarely do Unity games younger than April 2015
work for me. And it makes no difference whether it is a Linux
version or whether I try to start the Windows version using Wine.
I would have been interested to see if a Unity 4 version of
Chroma Squad would work for me.But I'm not prepared to put
a lot of effort into it. Maybe I wouldn't like the game anyway. *?
I bought 5 other games today.