The Unholy War was primarily a 3D fighting game, with a separate turn-based strategy mode included in the package. The fighting, known in the game as Mayhem mode, took place in a 3D arena in a similar fashion to something like Power Stone, allowing for full free movement of the character. Pick-ups, traps, hazards, teleporters, bounce pads, and more filled each arena, with some characters being better suited to different stages.
The strategy mode of the game took place on a hexagonal grid and was a simple turn-based affair where players could buy, move, and attack units, with the eventual aim being to destroy the enemy's base before losing your own.
The game takes place on the planet Xsarra, upon which dwell the native, and mostly monstrous inhabitants, the Arcanes. Another race, known as the Teknos, consisting predominantly of cyborg warriors, crash-landed on the planet, and upon discovering its rich resources, instigated a war with the Arcanes for control of Xsarra. The war lasted over two decades, before a truce was formed between the two races, calling for peace and civility, and allowing both races to live together harmoniously, with only one rule: no Arcane may have a child with a Teknos, and vice versa. After a few years of peace, an Arcane male falls in love with a Teknos female. The couple do not procreate, but their relationship is cause enough for war to re-emerge on the planet.
The game begins at this point, with the player choosing their side and attempting to win the war.
The story is only really relevant in the Strategy mode, with the Mayhem mode having no cut-scenes or exposition of any kind, and allowing for the races to fight amongst themselves.
- Brontu - A large, slow-moving Rhino-like creature, with the ability to unleash a shockwave, a charge attack, and a toxic gas cloud.
- Prana Devil - The blue, reptilian creature seen on the game's cover. One of the fastest characters in the game, and also one of the most fragile. Has the distinguishing ability to lay eggs in the arena, unleashing miniature Prana Devils to attack the opponent.
- Megaprana - An unlockable character. Essentially an upgraded version of P. Devil.
- Dark Angel - Has the ability to place crystals about the arena which heal him over time. It was a Dark Angel that coupled with a Quiksilver to cause the re-emergence of war.
- Magus Lizard - Has the magical abilities to summon meteors and birds to rain down on the opponent.
- Ecton - Able to place traps around the arena, and drain life. Demonoid in appearance.
- Mogalin Rider -
- Fire Witch - Also known as Edna. A demonic sorceress made of fire. She is able to place damaging fire traps around the arena.
- Killcycle - One of the most incredible characters in video games. A cyborg warrior physically attached to a hoverbike. Can fly, drop bombs, and, in dire circumstances, perform a self-damaging dive bomb attack for ultimate damage.
- Razorfane - Robotic warrior specialising in the use of circular saw-blades. Can place spinning razor traps.
- BetaRazor - Unlockable character. Essentially an upgraded version of Razorfane.
- Tesla Lord - Cyborg with the power of electricity, able to place shocking traps around the arena.
- Quiksilver - Silver humanoid character with the ability to change shape and form. Can create a shield around it, and transform its arms into devastating blades.
- Mantis - Large, insect-like robot. Can drain life and fly.
- Wasp - Similar to Mantis, but female, and more human in appearance. Is also able to drain and fly.
- Jaeger - The Brontu equivalent of the Teknos, a large, slow-moving tank that can fire rockets and lasers.