Full list of all 44 High On Life achievements worth 1,195 gamerscore. It takes around 20-25 hours to unlock all of the achievements in the base game.
The base game contains 32 achievements worth 1,000 Gamerscore, and there is 1 DLC pack containing 12 achievements worth 195 Gamerscore.
Kill Slumsley.
Get Knifey.
Defeat 9-Torg.
Take Knifey's advice and stab Gene in the gut.
Defeat Douglas.
Obtain Sweezy.
Use Sweezy to boss around the Office Moplets.
Defeat Krubis.
Obtain Gus.
Obtain the Jetpack.
Obtain Creature.
Defeat the Skrendel Brothers.
Obtain the Mag-Boots.
Defeat Dr. Giblets.
Pay your bill at Applebee's.
Spend 15 hours at the very real in-game alien strip club.
Defeat Nipulon.
Obtain Lezduit.
Say goodbye to Suit-O.
Sacrifice a Gatlian other than Kenny during the fight against Garmantuous.
Defeat Garmantuous and take down the G3 cartel.
Juggle an enemy in the air with at least 5 shots.
Pop 20 Grunt eyeballs.
Watch Globo's rise to fame.
Discover the movie theater.
Sit through the entirety of the really annoying countdown show on TV.
Discover Dr. Gurgula's hideout in the Human Haven.
Unlock and explore every collectible warp base.
Find and open every Luglox chest.
Unlock every post in the Bounty Hunter forums.
Collect every trading card in the game.
Complete the game with Stan's product in your inventory.
Collect all 9 trading cards on Peroxis and Muxxalon.
Defeat Mux.
Kill a Bloat with Knifey's new upgrade.
Take a bath with Toxxo.
Find a way to make love to the Parasite Passenger.
Visit Cheeks and hang out until closing time.
Visit every major Peroxian landmark (and report back to the tour guide!)
Find every scattered Muxxalon package.
Kill 100 enemies with a fully charged ball shot.
Become the Riddle Master.
Kill 50 enemies with Harpers glob shot.
Grant the dying wish of a sick slug.