Here is the full list of all 24 VolticPistol achievements.
You've started a new adventure!
Beat the game on easy
Beat the game on normal (must have never switched to easy mode)
Reach 100%
Beat New Game +
Beat the game with better than 40% hit accuracy
Beat the game with less than 9 deaths
Take down Marzdier
Take down Kyanite
Take down Zircon
Take down Serlimus
Take down Electricus
Take down Tharos
Take down Khantech, the King
Fight a boss playing as themself
Collect both ability pickups
Beat the first level under 2 minutes
Hit 4 consecutive downstrikes
Destroy all dummies in the training area
Collect all point pickups
Beat the game in HARDCORE mode
Hit 5 enemies with one energy wave
Reach 500 distance in the training room
Kill 1000 enemies