Here is the full list of all 25 Dexter Stardust : Adventures in Outer Space achievements.
Completed Episode 0
Completed Episode 1
Completed Episode 2
Completed Episode 3
Completed Episode 4
Classic point and click reference #1
Classic point and click reference #2
Classic point and click reference #3
Classic point and click reference #4
Classic point and click reference #5
Classic point and click reference #6
Venusian octopus defeated
Try to catch a rat bare-handed
Find a small coin
You gotta wait until episode 3 to explore the forest
Curious cactus connoisseur
Find a giant taco
Make your tacos even tastier
See the world in pixel art
Help a doggy out
Pick up superfluous inventory item
Solve a puzzle using all 4 ukulele chords
Earth eradicated
Solar system spectator
Ride the log ride back to the start