Crystal

Blue Crystal is the colloquial name for a parasitic alien lifeform that first appears in Primal Sands and also plays a key role in Don't Escape 3. The are a potent source of energy, but are highly infectious, festering and growing inside of other beings if touched or inhaled.

Appearance
The crystal emits blue light and subtle acoustic vibrations.

Primal Sands
The blue crystals are found inside the extraterrestrial creatures on the planet the protagonist's vessel has crashed on. They are used to upgrade the robot.

After successfully escaping the planet, the final shot of the game shows a member of the ship's crew, likely the protagonist, coughing violently, before hacking up a blue crystal.

Don't Escape Series
The crystal was found by the crew of the UEFS Horizon, attached to the bones of a space miner among the debris of another ship that had gone missing years earlier.

The crystal was brought on board and investigated in the lab by Dr. Amanda Grodberg. Too late did the crew find out the crystal was in fact a live organism, that survives inside of live hosts, growing inside them by consuming soft tissue. It infected one of the ship's pilots, and took over his body while he was sleeping, using him as a tool to murder the rest of the crew. It then tried to dispose of the pilot himself by ejecting him out the airlock, but the pilot woke up in time to stop the process.

The crystal can grow rapidly under ideal circumstances. At the start of the game, it has overgrown the isolation ward of the ship, so the pilot can't get in. Before her death, Dr. Grodberg created a formula for a mixture that weakens and partially destroys the crystal. The pilot is able to use this to shrink the crystal back enough to let him into the isolation ward.

Upon discovering the truth of what the crystal is, the pilot tries to destroy it with a makeshift bomb, either blowing up the entire ship or the large crystal inside the lab.

In Don't Escape 4 Days in a Wasteland, files found in the Sidereal plexus building speak of experiments performed on the moon involving crystals. The Sidereal Plexus website elaborates further on this, revealing that they have started a full-scale mining operation of the blue crystal for energy since the discovery of SP-1.