You woke up alone in a gloomy room with ominous marks of days on the wall. What's going on here? Where's everyone? You feel confused and unsettled, and all you can do is wander around to look for clues.
That's basically the story of Reach: SOS. The game has done absolutely a great job of creating the sense of being left alone. There's no background music, just sound effects of dripping water, waves, winds, etc. You can see traces of memories everywhere: photos, messages left by someone on the wall, doodles on the wall... Is this a shelter from what? Someone was living here, but where are they? You seem to be solving all the puzzles but your questions never get answered.
The game itself won't take long, maybe less than 20 minutes to finish. The puzzles are not that complicated, but it's more than just point-and-click. The interaction with objects sometimes does not work well and it's a little annoying. BTW I actually love the lack of background story here.
Anyway, if you love solving mysteries, you should never miss this!