We ARE going to have access to a DRM Free version as well, though ?? Non-Steam, that is ??
The goal is to have several versions, Steam, GOG, and Humble are all on the radar so, there will be a DRM-free version. It was important to us that everyone has equal access to the game across the board, which is why we didn't to paywalled content or paid "special items" in the game. Obviously Steam has certain requirements, however, we also want to ensure a DRM-free experience for those who want that level of flexibility.
You are paying for the game, so you should be able to play it unrestricted. All content, on whatever computers you want. Granted, mobile would be a bit of a stretch but, if you want to try running it there, go for it.