Here is the full list of all 27 Duke Nukem 3D: 20th Anniversary Edition World Tour achievements worth 1,000 gamerscore.
Kill 1000 enemies.
Find Sam in "Mirage Barrage".
Find Luke in the Level "Lunar Reactor"
Find the Doomguy in the Level "Death Row"
Finish a secret level.
Kill 5 bad guys with one shot.
Kill 10 bad guys in 10 seconds while on steroids.
Kill a Firefly Trooper while it's flying small.
Find 70 secret areas.
Complete "Shrapnel City" on any difficulty.
Complete "Lunar Apocalypse" on any difficulty.
Complete "The Birth" on any difficulty.
Complete "Alien World Order" on any difficulty.
Use the hookah in High Times.
Finish any level on "Damn, I'm Good" difficulty.
Kill every enemy on a level.
Step in a pile of excrement.
Burn 50 bad guys to death.
Complete "L.A. Meltdown" on any difficulty.
Finish the "Hollywood Holocaust" level in under 3 minutes.
Step on 40 enemies after using the Shrinker on them.
Tip an exotic dancer.
Carry all weapons with ammo at once.
Use the Incinerator
Use a cheat code.
Find a secret area.
Listen to Developer Commentary (Use at least one trigger).