Then apparently you need to buy the Planetary Annihilation game for only £68 - and its in early access mode, so stability and features could be all over the place...
Well you need to understand this game was funded via kickstarter and the pricing from that has transfered over into steam and has been explained by the developers.
As the game moves into beta and final release its price will drop down to about 20-30 pounds as with most games, if you want alpha access have to pay what the rest of the kickstater bidders payed.
Possibly though with this Alpha you get access to the PA Alpha forums and can shape the game through feedback- have been alot of community changes that the developers have implemented.
Their is also a series of video updates on youtube where the developers talk about the games development and the feedback from the community.