Here is the full list of all 63 Gunslugs achievements.
Blowup a death worm
Complete mission 3.1
Score 2500 points
Find the sketch world!
Drive over 10 dudes with a tank
Drive over 5 dudes with a tank
Collect 175 coins in one game
Kill a chicken, and spread some eggs!
Rescue B.A. Baracuda
Destroy four mechballs
Chain explosion of 3
Score 2000 points
Get your train ticket and ride.. or run
Rescue Sonya
Kill 50 guys in one mission
Blow up 4 dudes at once
Chain explosion of 2
Grab energy drink
Complete mission 2.3
Score 1000 points
Collect 150 coins
Kill 10 guys with grenades
Locate the arcade !
Take a jetpack ride
Find "a" princess
Kill 20 guys
Rescue Willis KiYay
Complete mission 2.2
Drive a tank
Rescue Sly Rocko
Complete mission 2.1
Collect 125 coins in one game
Score 500 points
Kill 5 guys from cover
Air kill a dude
Blow up 2 dudes at once
Complete mission 1.3
Complete mission 1.2
Find the voodoo priest
Collect 100 coins
Make a chopper crash
Kill 10 guys in a mission
Complete mission 1.1
Change the tune using a jukebox
Collect 75 coins
Grab a new weapon
Complete bootcamp
Deactivate your first beacon
Take cover rookie!
Complete mission 3.2
Complete mission 3.3
Complete mission 4.1
Rescue Sarge
Complete mission 4.2
Complete mission 4.3
Kill a flying fire skull
Complete mission 5.1
Kill 5 skulls in one mission
Complete mission 5.2
Destroy 5 hell tanks in one game
Complete mission 5.3
Complete Hell with Sarge
Complete Hell with BA