Mars

Mars is a planet in the Solar System which is featured in Plazma Burst: Forward to the Past, and is where the entirety of its campaign is set. In level 16, the Marine leaves Mars en route for Earth, a planet nearby. The planet is currently colonized by the Humans and Falkoks.

It is unknown what purpose Mars serves to the humans. For Falkoks, it has been shown that it is home to one of their bases, as shown with the presence of the Falkonian Ship at the end of the first game, which shows that space craft are stationed there. It is known that Grubs are native to Mars, and are possibly only found here.

Humans
The group of humans appear to be the main or only human presence of humans on Mars. It is unknown what purpose they are there for. The humans on the planet are known to harvest Grubs (a lifeform which is possibly indigenous to Mars) which are then trained to fight on behalf of them, however.

Falkoks
The Falkoks appear to have a large military presence on the planet, as evident by their troops which are hostile to any intruders. The Falkoks are also shown to go as far as to launch a Sword Bot against the Marine and Noir Lime, which implies that the base is of high importance to the Falkoks.

Trivia

 * In PB:FTTP, some cutscenes are shown which feature the surface of Mars and the Earth.
 * The distance between Mars and the Earth in these cutscenes is very unrealistic.