Developer MercurySteam celebrates the 1st anniversary of Raiders of the Broken Planet's open beta, so all three campaigns of their online action-adventure game are free for a limited time on Steam.
To get the campaigns, you only need a Steam account or just click the download button on the links below. Once you get them, they will be yours forever. The offer ends on Friday, May 25.
The base game is free-to-play: