You're a surgeon from Earth who's been beamed up to a spaceship, and forced to operate on aliens. Each passenger has some incorrectly connected internal organs, as well as one organ that shouldn't be there at all. It's your job to reconnect the organs sufficiently as well as disconnect the organ that's out of place.

Do well enough, and you might actually return home to Earth...

Organs lose health slowly if they're either: not supposed to be inside the alien, or not connected to the correct organs via tubes. Click and drag organs and the ends of tubes to move them around.

You can use the freezing lever to stop organs from losing health, but you won't be able to connect/disconnect anything. Use this if you need to take a breather or check the health of each organ, but be wary - you have limited freeze resource per alien.

Use the scanner to check how much health each organ has. You cannot connect/disconnect anything while scanning.

You are scored based on organ health, whether each organ is connected correctly, and if the organ is in the right place (approximately).