Of course they tested Doom :-D

They might also run Linux kernel 3.7, that supported i386. Gray386linux is still maintained, and runs a patched 3.7 kernel.

https://github.com/marmolak/gray386linux

Doom (DOS extender games) is an easier protected mode application as it does not use complex page tables. Linux is much more complex.

haha, this was my first thought when I read the headline, because this "classic test" always comes up here :-))