Indeed it is!

Looks like they are charging people who want to play early and then when the game is out of early access it will be free.

http://steamcommunity.com/app/512560/discussions/0/152393186481007518/#c152393186491110817

Hello guys, i'm one of the developers and i'd like to make it absolutely clear - the game will be F2P in OBT and after the release. For now it's CBT and the price you pay is for invitation. Nobody forces you to spend your money for unfinished product, but we appreciate any purchases and will make some gifts to the participants of CBT. As for the price in English store - we never set it that high (14$) and in Russian store it's less than 5 bucks, so for that surcharge you can only ask Steam. Thanks for your consideration