In a recent announcement, Twitch has revealed that Headlander will be free on PC for those subscribers who upgrade their subscription to Twitch Prime. In the latest blog post, https://blog.twitch.tv/twitch-prime-members-head-for-the-stars-in-headlander-40b49470ccd7 the company revealed that the game is free for those subscribers with a Twitch Prime membership.
Headlander was first launched for PC, PS4, and Xbox One back in July 2016. Upon its release, the game received critical acclaims. In case you are interested, you can check out the game for free by going here.