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.
Character Colors
You can adjust your character's color palette once you collect four golden skulls.
Commander Video
To unlock Commander Video, collect 6 golden skulls.
Curly Brace
Collect 30 golden skulls.
El Testigo
Collect 26 golden skulls.
Jim Hawkins
View the "true ending".
Juni
Collect 18 golden skulls.
Pokemon Reference
After you clear the first world, a long cutscene follows. Aban will talk about the temple of Poko-mum and mistakenly refer to it as Pocket Monster, which was the original name for Pokemon.
President Thompson
Collect 20 golden skulls.
Sugimoto
Collect 16 golden skulls.
Tina Hawkins
Complete the Ukampa Ruins.
Tower of Nanar
To unlock the cooperative mode, Tower of Nanar, collect 5 golden skulls.
