Complete the following secret 37 achievements to unlock Xbox Live Gamerscore points.

Unlockable - How to Unlock

Carvahall - Hard (30 points) Make it through the Carvahall level on Hard.
Carvahall - Normal (20 points) Make it through the Carvahall level on Normal.
Daret Bridge - Hard (30 points) Make it through the Daret Bridge level on Hard.
Daret Bridge - Normal (20 points) Make it through the Daret Bridge level on Normal.
Daret Docks - Hard (30 points) Make it through the Daret Docks level on Hard.
Daret Docks - Normal (20 points) Make it through the Daret Docks level on Normal.
Daret Town - Hard (30 points) Make it through the Daret Town level on Hard.
Daret Town - Normal (20 points) Make it through the Daret Town level on Normal.
Gil'ead City - Hard (30 points) Make it through the Gil'ead City level on Hard.
Gil'ead City - Normal (20 points) Make it through the Gil'ead City level on Normal.
Gil'ead Keep - Hard (30 points) Make it through the Gil'ead Keep level on Hard.
Gil'ead Keep - Normal (20 points) Make it through the Gil'ead Keep level on Normal.
Ra'zac Chase - Hard (30 points) Complete the Ra'zac Chase level on Hard.
Ra'zac Chase - Normal (20 points) Complete the Ra'zac Chase level on Normal.
The Spine Mountains - Hard (30 points) Make it through the Spine Mountains level on Hard.
The Spine Mountains - Normal (20 points) Make it through the Spine Mountains level on Normal.
Trapped! - Hard (30 points) Complete the Trapped! level on Hard.
Trapped! - Normal (20 points) Complete the Trapped! level on Normal.