The Ice Planet is a planet that appears to be covered with ice. The elemental enemy in it would be the Ice Elemental. At some point, the player would have to approach two black monoliths that are on the other side of a bridge made out of ice. What their purpose was is unknown.
According to the list of levels found in Test 1, the player would be sent to the Ice Planet after finishing the Green Planet. It would be divided into two levels, Ice and IceEnd. After completing IceEnd, the player would be sent to the Tropic Planet.
The Ice Planet was completely removed from the final game. The only evidence of its existence can be found in the Test 1 co-op level list and a few pre-release screenshots.