Here is the full list of all 26 SPINGUN achievements.
Beat the Flamer Zone
Complete ALL Zones, WOAH.
Beat the Chainer Zone
Beat the Beamer Zone
Beat the Pulser Zone
Beat the Sploder Zone
Survive 2 Minutes in Endless
Beat the Super Boss
Complete ALL Bosses, WOAH.
Beat the Mega Boss
Rack up 1337 kills
Beat the Spreader Zone
Clear ballpit in under 30 seconds
Survive 30 Seconds in Endless Hardcore
Beat the Flasher Zone
Beat the Ultra Boss
Brrrrr!
Survive 60 Seconds in Endless Cursed
Beat the Homer Zone
Survive 60 Seconds in Endless
PEACE BROTHER
Only the good ones die young...
Survive 30 Seconds in Endless
Wow, how creative!