Unfortunate Spacemen All Hidden Achievements Guide

This achievement is found on the map H2O.
It begins with you walking towards the top left corner of the map.

Once there, you should find a rock. You will be able to simply walk past the limits shown on the player map. The actual map border is much farther away. Walk north of the top left corner, until you pass the rock.

Behind this rock, facing away from the main building, should be the Dopefish inside a scuba helmet!

This achievement is found in the Spaceman Tutorial.
Begin the tutorial, and continue until you arrive at the shooting range.
Pick up the gun.
Turn around 180 degrees, and you will find a camera. Shoot and destroy it, and you will get the achievement!

This is the easiest achievement, because it doesn’t even require you to start any kind of game.
You begin at the start screen, and go to the top, where it says “Tutorials”
In the Tutorials tab, click “How to Play Guide”
Once at that screen, you should get the achievement.