Sub Terra is a puzzle game by Crystal Shard and can be downloaded here. Not to be confused with a film Subterra or with a game Subterranean Animism. The game's main objective is to get gems and then reach the exit, while any number of lethal obstacles get in your way, such as falling rocks, dragons, explosions, fire and water, and floating skulls. The obstacles include the gems themselves, as a gem falling on your head will kill you. Depending on the level, you need to use careful planning, quick reflexes, or both. The game incorporates many elements from Boulder Dash, Chip's Challenge, Sokoban, and Laser Light.