Here is the full list of all 24 XEL achievements worth 1,000 gamerscore.
Defeat the rusty Overseer.
Get your hands on the bio synth silk dispenser.
Enter the Bog.
Enter the Glacial Glades.
Solve the mystery of the Science Station.
Enter the Scorched Wasteland (without burning to crisp).
Smash the revolution.
Put an end to the madness.
Collect all Health Seeds.
Collect all Stamina Seeds.
Upgrade your Sword to the max.
Upgrade your ZapTrap to the max.
Upgrade your Webshooter to the max.
Upgrade Chap to the max.
Upgrade Burnhilde to the max.
Upgrade your Clubber to the max.
Upgrade all Gadgets to the max.
Master all cooking recipies.
Parry for the first time.
Parry 100 times.
Travel to "that strange place" for the first time.
Collect all audiologs.
End your adventure without any upgrades (except THAT ONE for Chap).
Collect all Achievements.