Here is the full list of all 17 Bad Pad Demo achievements.
Finish the second carting level
Finish area 1.2
Get glow in dark upgrade
Win your first battle against Evil Pen
Finish the first carting level
Meet Analog, he will help you!
Open and go through your first door
Collect your first coin
Blow up your first rock
Find and talk to TrapeZoid
Think you're a good runner, try Bad Run!
Finish area 1.3
Get Drop Bash upgrade
Defeat Evil Pen again
Collect 20 coins
Win your first arcade mini-game
Finish the demo