In order to unlock the Bucket Head achievement, you must first find all three helmets in Duke Nukem Forever.
Here are guides on how to find them:
1. The first helmet is the Halo: Master Chief’s Mjolnir battle armor helmet.
You must load the Las Vegas Level.
Once finished loading, you would automatically find the first helmet at the beginning of that level.
(The helmet is located at the left side of the EDF-Soldat)
2. The second helmet is the Dead Space: Isaac Clarke’s engineering suit helmet.
First load the Hive.
Then go forward to the scene.
Once you enter, take a left turn and there you will find the second helmet.
3. The last helmet is the Borderlands: Bandit Raider’s gas mask helmet.
You should first load the Underwater Level.
Then plant the bomb to destroy the gate and use the wheel. Afterwards, move forward.
There you will find the last helmet.
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