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