Here is the full list of all 31 Headlander achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Drained all of the Energy S.A.C.s
100% Headlander
Found all alpha, beta and gamma terminals
Popped your head into every room to have a look-see
Unlocked all upgrades
Found a power gem charging Shepherd and returned it to Rhea-6
Found all mid-range zap locations
Took Methuselah offline
Defeated the Methuselah titan
Used Overcharge Boost to take out 25 enemies
Found the entrance to Methuselah's Core
Found your body and witnessed ERL's sacrifice
Found all the bodies for Athena-7
Kill Mappy without taking his Data
Used the long range zap to Luna Citadel
Defeated the Kill Queen
Executed 50 headshots
Uploaded the Archive Data to Earl
Shut down the power stations in the Power Dome to gain access to the Archives
Eradicated the Spectrum Shepherds
Destroyed 25 enemies using melee attacks
Aligned the Satellite Chalet dishes to gain access to the Archives
Found Frank the Dog and return him to Eudora-5
Thrusted through the Pleasure Port to find the Satellite Chalet
Escaped the Starcophagus to crash land on the Pleasure Port
Used explosions to kill 5 enemies
Execute all possible dance subroutines
Boosted for 5.2155e-13 parsecs (10 miles)
Used Auto Sentries to take out 10 enemies
Docked with every body type
Played a game of H.O.R.S.E.