Download of RadiationIsland 1.0.6 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. This Mac app was originally developed by Atypical Games. The software belongs to Games. We recommend checking the downloaded files with any free antivirus.
From the developer:
Radiation Island is a survival adventure game where you craft your own destiny in a huge open world environment. As part of the Philadelphia Experiment, you have become stranded in a parallel, alternate reality. You need to discover this new and mysterious world. You can use everything you find to survive it and solve its puzzle to get back to the real world.
You may want to check out more software for Mac, such as JackKeane, Wandering Willows or DepthsOfPeril, which might be similar to RadiationIsland.