You wrote "... the Linux version is untested", so I thought I'd let you know my experience. I unpacked Autonauts_Version_10_Linux_Universal.zip into a folder under usr/local/ and used
$ chmod -R u+x
to make sure that the executables were, um, executable.
I ran Autonauts.x86_64 successfully for about an hour, with no issues at all, except perhaps that the sound effects continue when using Esc to pause the game - that may be a feature, I don't know!
There are some system details below, in case that helps with the Linux version - I'd like to think that you'll continue with it.
KDE Neon 5.8; kernel version 4.10.0-33-generic; AMD Phenom II X4 965 CPU; nVidia GeForce GTX450 GPU with nVidia-375 driver; 4GB RAM