https://play.google.com/store/apps/details?id=com.threeminutegames.lifeline.google It's cheap at the moment, but even at full price it's still worth it. It's like one of those choose your own adventure book things, but with a tiny twist. Basically, a guy crash lands on a moon, sends out a distress signal which is picked up by your phone. You start conversing with him and at various points along the narrative, he asks you to make choices or research stuff for him. It lasts about 3 days all in all, but it's very engaging and so far has a couple of different endings. Totally worth a download.