I actually commented on Polygon about this too, but...
The game is ARM only, which means they’re ignoring the larger chunk of their potential audience that would be running Windows 8.
It’s also a 6-month old game that has been available for PC for that whole time on Steam anyway.
Quite frankly, on top of that, it’s a turn-based strategy game, which narrows down the number of people who would play it even more.
There’s more involved in this not selling besides just Microsoft not promoting them. I mean, has the company tried any promotion on their own until now? No. Have they thought about updating their website to have more than just a small icon at the top about Windows RT? (Hint, it might be a good idea to update "Available now for iPad, iPhone (HD and SD), and Android. Coming soon to Windows PC, Mac, and Blackberry playbook.")
I mean, I’m sure sales aren’t what they were hoping for, but to whine about how it’s because Microsoft isn’t helping them is ignoring a lot of factors. Of course, it did exactly what the developer was hoping for… free publicity on lots of gaming websites, and their blog about it has now been pulled because they got Microsoft to contact them.