The game itself is similar to Minecraft, it's not voxel based but you can still mine, dig, chop down trees to collect wood, build different structures. You have a great variety of things to craft and it's really crucial that you take care of your health, because fixing a broken leg, an open wood or poisoning isn't that easy at all if you don't have the right materials.
The game has a story and a sandbox mode. In the story mode you can visit several islands, complete missions, meet strange characters and of course survive. In the sandbox mode you can choose the size and the type of the island, and start being a cast away without any particular goal apart from being alive. The game is really fun and can entertain you for many hours, it's really atmospheric, the simulation is working and it also has some laugh out loud moments like setting a turtle on fire and watch it being cooked while it's still walking around.
The game is free and very small, it will run on almost any computer, you don't need a high capacity machine in order to run it. As of 2012 the developer started to work on Stranded III so the saga continues. Check out the developers website, download the game: