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