Yes. The game was Kickstarted and their goals were clear. The successful campaign shows that most gamers that like such games are on PC. I dare to say >95% of the market.

The game type also makes little sense on tablets and smartphones and the hardware requirement are too high to support them.

Porting to console is time consuming if you are not developing with Unity or equivalent.

Quote from their kickstarter: We have announced a stretch goal for a Mac version of the game. If we reach the stretch goal of £1.4 million through the Kickstarter we will release a Mac version approximately 3 months after the Windows PC release. It was reached.

I'm more disappointed about the no Linux myself. Though probably Wine will be able to run it, it manages a lot these days.

Tablets and smartphones? This isn't Candy Crush or Angry Birds here