Here is the full list of all 17 Tower of Guns achievements.
Pick up 1000 Health Items While at Full Health
Kill That Dang Wall of Turrets Three Times
Die while a Boss is Exploding
Jump and Remain Airborn for 45 Seconds
Pick up Four Difficulty++ Badges in a Single Life
Complete a Stage Without Anything but the Boss dying
Complete a Stage After Firing Exactly Fourteen Shots
Reach Endless Stage 14
Unlock all the Guns
Unlock all the Perks
Accumulate 888 Gold In a Single Run
Find and Level The Motivator Gun to Level 5
Complete a Stage without Picking up ANYTHING
Discover the Secret Code
Kill over 350 Mobs in a Single Level
Stomp a Hugbot to Death
Tilt 10 Times in a Single Stage