The game was officially released as freeware in 2004, and the graphics have been made available under an open license in April 2007.
A peculiar feature of Tyrian is that it is very forgiving of enemy hits: before the player's starship is destroyed it must take enough damage to exhaust several points of shields and armor (the difference is that shields regenerate during play while armor is recovered only with specific powerups and between levels).
Another unusual characteristic of the game is that weapon powerups are very rare: main weapons, sidekick weapons, and equipment such as shields, energy generators (which determine how fast weapons fire and shields recharge), and different ships are bought in interlevel menus; front and back weapons can be upgraded or downgraded at each of 13 power levels. Available money corresponds directly to score.
The multiple linked weapons, the equipment-buying system and the shield/armor hit points in Tyrian are similar to game mechanics in Raptor: Call of the Shadows, another PC game from the same period.
Tyrian was a departure from the prevalent "serious" style of shooters, due to the cartoon-like artwork and the abundance of silly (or at least strange) dialogue and content.
The main mode is the single player Full Story mode. This mode also includes storyline-related messages for the player to read. The player begins with one standard weapon, which may be upgraded or replaced by a large variety of weapons, including weapons such as multi-directional cannons, lightning guns, beam lasers, heavy missiles, and homing bombs. There are primary and secondary weapons, where primary weapons are mostly limited to forward arcs, while secondary weapons often come with wider coverage, including side and rear shots. Both types of weapons have eleven levels, making them upgradeable 10 times, although higher levels cost exponentially more.
Additionally, the player can purchase up to two "sidekicks" which fly alongside the ship and can fire independently of the main ship, but are still controlled by the player, and not the AI. Examples of sidekicks include powerful atom bombs, mini-missiles, and multi-directional mines. Other upgrades include increased shields, more powerful generators which can increase firing rate as well as shield recharge, and ships with more armour and/or higher maneuverability.
Any weapon can be upgraded in stores, even if not available for sale, and any item can be sold without loss, so the practical function of shops is not trade but letting the player build a strong ship on a budget (with no penalty for failing and trying a different build). The player cannot obtain sold items again without reaching a level which offers them, in many cases a single secret level in the whole game, so selling very good items is generally bad; in the first loop through the game the player usually gets and keeps forever the best ship, shield, generator, sidekicks and special weapon (choice of the two main weapons depends on personal style and level needs).
The ship, shields, and generators are not upgradeable, although the player is given a medium attribute ship.
Both ships had differing abilities. The Dragonhead had more main weapons at its disposal, and also controlled the "special" powerup weapons. The Dragonwing, by contrast, controlled sidekick weapons and utilized a unique "charge-up" system for frontal offenses. If the player does not fire, power will charge, visibly shown as 1) blue particles gathering in front of the ship, culminating with a blue sphere with two orbiting particles in the front of the ship, and 2) green lights moving in succession on the control board on the right of the screen. There are five charge levels for each weapon, and collecting the spherical purple powerups will give the Dragonwing the ability to charge-up faster, to the point where the maximum charge is reached within a second or two.
One day, Buce Quesillac, a Hazudra, and Trent's best friend, is shot in the back by a hoverdrone which quickly disappears into the sky. As Buce lay dying, he tells Trent that it was all the work of Microsol, the giant corporation who controlled the terraformation of Tyrian. They had Buce shot because of his knowledge of Gravitium, which is a special mineral, unique to Tyrian, capable of controlling the force of gravity.
Microsol want to utilize Gravitium to power their warships, which could result in them becoming nearly unstoppable. They also attempt to eliminate anyone who knows of its existence. Trent is the next person on their hit list, and with his last words, Buce implores him to try to reach Savara, a free world. Trent manages to secure a small fighter, and departs for Savara.
The first mission covers Trent's escape from the planet Tyrian. As the game progresses, transmissions are received from allies and enemies alike, each one advancing the plot. Eventually, Trent comes into contact with a rival of Microsol's; a corporation called Gencore. At the end of the third episode, the player must fight their way through the Microsol battle fleet and destroy the main ship.
The fourth episode, which was added with version 2.0, entails the activation by Microsol of an ancient alien computer system located under the surface of the planet Ixmucane. This system was designed to turn the planet into a sun, but was never activated by its creators. The player must destroy the system before it fully activates, so that Microsol does not gain even more power. In addition, many important scientists are trapped under the surface; they will die if the system fully activates.
Following the final battle, Trent grows tired of being given orders and sent on dangerous missions by his superiors. He sets course for Earth, which is 100 light years away, and goes into cryonic sleep.
In the fifth episode, added in Tyrian 2000, it is revealed that the Hazudra strapped a proximity bomb to Trent's ship to send him in another direction than Earth. They then use Trent to take out the Zinglonites, who invade space with space-dwelling fruit. The new episode also featured new ships, shields and weapons to complete that task.
The origins of Tyrian began as an experiment in 1991, with a young Jason Emery showing his friend Alexander Brandon the preliminary workings of a scrolling background. The two continued developing, and eventually decided the work could be shown to a game company. Brandon wrote a proposal document and sent it to the two leading shareware game publishers of the time, Epic MegaGames and Apogee. However, the game lacked any sound or music, and the graphics were "definitely not professional". As such, "neither got overly excited", but both showed interest.
The two developers thought they would never find a publisher. However, after a long wait, Robert Allen—head of Safari Software—considered Tyrian to fit perfectly with their company, which handled smaller scale projects. Robert Allen had word from Cliff Bleszinski that Tyrian was very similar to Zanac, thinking that it should be followed up.
Robert Allen gave leads to sound coders and artists, the first being Bruce Hsu who created interface graphics and character faces. Artist Daniel Cook was hired after composer Alexander Brandon showed interest in his artwork, which was—unbeknown to Cook—"sent around" by a friend. After he was sent a short list of levels, Cook created sample artwork on an Amiga 1200, with a David Letterman episode inspiring "some weird stuff". It was met with praise by the other developers, who asked him to "make some more!". The artwork was completed in a 4 month period.
After work began on graphics, the popularity of Tyrian rose at Epic MegaGames. Arturo Sinclair from Storm Front Studios joined to create rendered artwork for planets and character faces. The developers wanted a "simple and fun solution" for the interface, and changed it at least three times before deciding on a final design. At this point, Tyrian was almost complete; with the "LOUDNESS" sound system, near-completed sound effects, and a marketing plan head by Mark Rein. At this time, Tim Sweeney approached the team and informed them Tyrian was to be published as a full fledged Epic MegaGames product. It was later released in 1995.
Most recently, it has been released for the Nintendo Wii (as a port of the hacked GameCube version of the game.) It is a direct game port due to it emulating LinuxOS for GameCube.