Here is the full list of all 23 Purple Chicken Spaceman achievements worth 1,000 gamerscore.
Played into the wee hours of the night
Finished the game a second time
Finished a Level Without Getting Hit
Didn't shoot for 30 seconds and didn't get hit
Beat a level without using a powerup
Beat Attack on Earth!
Beat the game
Beat L4Z0r C4t for a second time
Beat Alien Holmworld
Beat Ocean Scenes
Beat Heck
Beat Frosty Fields
Beat Desert of Desserts
Beat Goosebump Gorge
Killed a boss with a smartbomb
Used a shield for the first time
Beat Neptune's Crypt
Beat Outer Space Panic
Used a smartbomb for the first time
Successfully dodged the wobbly powerdown
Got rid of the shakes!
Got your first wobbly powerdown
All you gotta do is play!