Here is the full list of all 11 Alexio achievements worth 1,000 gamerscore. It takes around 0-0.5 hours to unlock all of the achievements on Xbox One.
Complete the level 1
Buy anything from the cat
Defeat 20 enemies
Defeat 10 enemies
Die 10 times
Die once
Complete the level 0
Defeat an enemy
Jump 150 times
Jump 72 times
Jump 10 times