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