Full list of all 15 ilomilo achievements worth 250 gamerscore. It takes around 8-10 hours to unlock all of the achievements in the base game on Xbox 360.
The base game contains 12 achievements worth 200 Gamerscore, and there is 1 DLC pack containing 3 achievements worth 50 Gamerscore.
Played the solo instrument to the music theme in the main menu
Helped find all 10 floating eggs with the fly while playing cooperatively
Completed the game
Completed all bonus levels
Advanced to chapter 4
Defeated a Nabber in the same move as you completed a level
Advanced to chapter 3
Advanced to chapter 2
Collected one safka of each color
Completed the tutorial
Completed a level
Get a score of 500 points or more in the ilomilo shuffle minigame
Complete autumn tale (autumn tale)
Complete all bonus levels (autumn tale)
Point on all the 5 floating eggs with the fly while playing cooperatively (autumn tale)