Xardion tells the tale of three warring planets that are home to three distinct alien races. Their fighting is interrupted by the threat of invasion from a much more potent alien race. The three planets find that they are able to set aside their differences long enough to battle their shared menace.
The single player controls one of three characters - Triton, Panthera, and Alcedes - each with unique abilities. There's also the option to switch between them at any time. If a character loses all health, the player is sent back to the start of the level, and that character regains some health.
Each character has special attributes and can gather power-ups and weapons to aid in their mission. For example, Panthera's small size allows him to access areas other characters cannot. The goal is to work together with each character's strengths to overcome challenges.