Blackthorne is set on the planet Tuul, which has existed for hundreds of years without human knowledge. All of this time, Tuul's people have been ruled over by a single shaman who "was blessed with all knowledge". Years before the game begins, Thoros, the latest ruler, finds it near impossible to choose between his two sons as the next ruler. Believing it will solve the dilemma, he leads them to the deserts and kills himself. His body becomes two stones, light and dark, and he gives one to each boy to rule their own kingdoms respectively. The people of the lightstone form the kingdom of Androth, and the people of the Darkstone form Ka'dra'suul. But while Androth respects their stone, Ka'dra'suul reject theirs, and are eventually transformed into monsters by it. In this time, a ka'dra named Sarlac seizes power. He forms an army and leads them against Androth. Knowing of his people's doom, the ruler of Androth, King Vlaros, with the aid of the Androth magician Galadril, sends his son Kyle to Earth to save his life. Vlaros also gives Kyle the lightstone for safe keeping. He wishes that Kyle can one day return and use it to save their people. 20 years later, Kyle has become a renowned military captain and mercenary. After breaking out of prison facing court martial, Kyle begins having strange dreams, and eventually is reconfronted by Galadril. He is told that it is time to return to Tuul and save his people. The game begins here with Kyle setting out to kill Sarlac and reclaim his throne.
Blackthorne was released for the SNES and MS-DOS in 1994, and with enhanced graphics and a higher color palette for the Sega 32X in 1995 and for Mac OS in 1996. The version for the Game Boy Advance was released in 2003.
The game focuses around protagonist Kyle Vlaros who is known as the Blackthorne, out for revenge on Sarlac and his minions. The gameplay involves large platforming sequences, in which Kyle can run and climb around the environment, find keys and items and progress to the end of each maze like level. Combat in Blackthorne takes the form of gunfights. Both Blackthorne and his enemies can press against walls to avoid incoming bullets. Blackthorne can also fire blindly behind himself.
The game has seventeen levels within four areas - the mines of Androth, the Karrellian forests/swamps, the Wasteland desert, and Shadow keep. The Sega 32X version includes a fifth area, the snowy mountains, which is not found in the other versions of the game. As the game progresses through these areas, Kyle becomes stronger and better armed, but so do the enemies.
During the game, Kyle uses a Pump Action Shotgun as his primary weapon. As the game progresses, Androthi allies will help him upgrade the weapon, increasing its speed and power. Kyle also finds many other useful items.
- Bridge Key - A gold key that activates a force field bridge at certain pedestals. Bridge keys can be removed from these pedestals and reused elsewhere as well.
- Iron Key - A key that deactivates laser fields that cannot be removed by destroying a generator. An iron key opens any lock, but can only be used once.
- Hover Bomb - When thrown, this bomb lights up and rolls along the ground and up walls until it reaches a target. It is useful for killing enemies, but in some levels it must be used for blowing open doors or destroying power generators. Some levels cannot be finished if the player uses a hover bomb at the wrong time.
- Fire bomb - These bombs explode the second they touch the ground and damage everything for a distance in the direction it is dropped. It does not necessarily destroy what it hits like the hover bomb. It will weaken enemies, but not kill them. It is most helpful against carnivorous plants that would do the player harm.
- Levitator - A collapsible platform that vertically extends to help the player get to an otherwise out of reach place. It is also useful for getting out of the line of enemy fire.
- Potion - A potion that restores the player's health to its maximum capacity. As the game progresses, they become more difficult to find.
- Remote Wasp - A wasp-shaped bomb that can be flown by remote control. Like the hover bomb, it is useful for killing enemies, but is often necessary to destroy out of reach generators that power laser fields. A purple goblin-like enemy creature uses remote wasps against the player; the player usually obtains wasps by killing one of those creatures.
Grag'ohr, usually just called orcs or goblins, are the most common enemy Kyle encounters. They use rifles, purple ones use remote wasps as well. They can also punch Kyle if Kyle stands too close to them. They also withstand varying amounts of damage before dying, depending on the color of their skin.
Whar'orks are large blue demons who are usually found around slaves. They use a whip as their weapon, and are armored heavily to the point where only a hover bomb can defeat them.
Spider Mines are a hazardous enemy found across the entire game. Kyle has to jump over them as they approach or they will detonate.
Eekers are tentacled plants found in the last three areas. Usually, Kyle can just avoid them. If caught in one, however, he will either fight it off or be eaten (depending on the amount of health he has).
Andromedogs are Androthi traitors who work for Sarlac, appearing in the last three areas of the game. They carry pistols and attack Kyle or other Androthi on sight. They also can kick Kyle if Kyle stands too close to them. Much of the second chapter involves all out fighting between Androthi rebels and Andromedogs.
Golems appear later in the last two worlds. They disguise themselves as rocky statues found in levels, and can roll into a ball-shaped boulder. Gold Golems are encountered first, then Silver Golems in Sarlac's castle.
Sarlac, the villain of the game. He attacks in various ways such as stealth, strong punches, magical blasts, and orders his guard beasts to drop exploding orbs. After Sarlac is defeated, Kyle takes his skull for a trophy as shown behind his throne chair at the end of the game.