Here is the full list of all 23 Clockwork achievements.
Fix a Leg
Kill a Shambler
Place a Portal
Beat the First Boss without Dying
Finish Act 01
Fix the Generator
Solve a Puzzle with a Sentry
Play the Game for Two Hours
Idle for 5 Minutes
Use a Portal
Die during the Act 1 Boss Fight
Die 5 times in one level
Solve a Puzzle with a Shamblebot
Control Milli
Solve a Puzzle using a Time Remnant
Finish the First Level
Play the Game
Finish Act 02
Finish Act 03
Finish the Game in One Session
Beat the Final Boss without Dying
Die during the Act 3 Boss Fight
Solve a Puzzle with a Box