The game follows astronaut Taylor, who strikes up a conversation with you after they crash land on an alien moon. It's up to you to make decisions that will keep Taylor alive.
Interestingly, the game plays out in real time so you may have to wait hours or days for the next message to come in. You'll get a notification, and can respond directly from your iOS lock screen. It's even better on Apple Watch, as you can play the entire game from the wrist-strapped 'puter.
We called the game "a short but unique and enthralling piece of interactive fiction" in our review.
The game just got updated with a new Lifeline short story - featuring an elite group of Marines on Tau Ceti - written by Dave Justus. And, even better, it's now free.