1001 Spikes

Obtain the Key of Serpentis, then play level 10-7, "Jokulkyrkja", in Antarctica. Jump on the platform with the strange serpent symbol and it will lower into a Boss fight. Defeat the boss by throwing knives at the crystals on the ceiling in order to break each section of the dragon platform you are riding on. After the Boss has been defeated you will unlock Antarctica for all characters, Jim Hawkins, and the alternate ending.

Complete all Akumpa Ruins levels. To unlock Antarctica Temple for all characters, view the True ending.
lha, r itd hyv ueyigner

Complete the indicated task to unlock the corresponding character.

Commander Video: Collect eight Golden Skulls.

Curly Brace: Collect thirty Golden Skulls.

El Testigo: Collect twenty six Golden Skulls.

Jim Hawkins: View the True ending.

Juni: Collect eighteen Golden Skulls.

President Thompson: Collect twenty Golden Skulls.

Sugimoto: Collect sixteen Golden Skulls.

Tina Hawkins: Complete Ukampa Ruins.

Zombie: Collect twenty three Golden Skulls.

You can find the Key of Serpentis in level 2-1, near the exit door. It only becomes accessible after unlocking Antarctica and when using Aban Hawkins, the main character.

Play level 2-1, "Rush into the Ruin", at the Ukampa Temple. One the right side of the exit is a unique block with a key symbol. Remove the key block and enter the new area to the right of the exit. Note: Removing the block may require all Golden Skulls. The Key of Serpentis can be found in the center of the temple area.