Xevious tells the story of the fight between humankind and the supercomputer GAMP, which controls the alien forces of planet Xevious. As the sci-fi cliche dictates, it turns out that the Xevious inhabitants are originally from Earth, and GAMP (General Artificial Matrix Producer) is the product of an ancient civilization that prospered on earth a hundred thousand years ago. During this golden age, the Gamps were human clones used in heavy labor, until they rebelled to their own creators. In order to survive the upcoming Ice Age, they planned to leave earth and migrate in search of a new homeland. They finally selected seven planets that were likely suitable to human life.

Right before the departure, a group of humans rebelled and decided to stay on the earth anyway. It is from here that thousand years after the leaving of the Gamps that the brave pilot Mu and his android companion Eve decided to travel to Xevious (literally, the fourth planet) to avoid glaciation. They would not receive a warm welcome from their ancestors, though: captured and imprisoned, they discovered that the Xevians were actually planning a massive comeback on the Earth.

Fast forward to our days: all above the Earth's surface, and near the ancient civilization remains, giant artifacts suddenly emerge from the soil and activate: they are SOL towers, buried underground and inactive for eons, now responding to GAMP's orders. The invasion has begun: it is now that, with perfect timing, Mu, Eve, and Mio Veetha, a Xevian who opposes to the Gamp's regime and freed our duo from prisoning, are back on the Earth (space travel takes all this time, you see) on their Solvalou ship and ready to fight Gamp's army. Meanwhile, archaeologists Susan Meyer and Akira Sayaka discovered that the Nazca lines could be hiding an ancient weapon that may be used to counterattack Gamp's army.

Xevious was one of the earliest vertical scrolling shooters (it was preceded by at least the 1981 Atari 8-bit computer game Caverns of Mars) and greatly influenced games in this genre. The graphics were revolutionary for their time, and characters were rendered with remarkable clarity and effect through careful use of shades of gray and palette-shifting. It was one of the first games to have hidden bonuses which are not mentioned in the instructions but can be revealed by a secret maneuver. Among these was the 'special flag' which first appeared in Rally-X. In this game the flag gave the player an extra life and this feature was carried over to numerous subsequent Namco games. In 1983, the original Xevious was the first arcade game to actually have a television commercial aired for it for the North American market. Atari promoted the game with the slogan "Are you devious enough to beat Xevious?" and closed the commercial with a tag line branding it "the arcade game you can't play at home." This may have been the first TV commercial for an arcade video game. Atari also produced a TV commercial, specifically for Xevious.

While it saw limited popularity in the U.S., Xevious was a huge cult hit in Japan. Popular musicians Haruomi Hosono (Yellow Magic Orchestra) and Keisuke Kuwata (Southern All Stars) were known to be fans of the game, and the former produced an album of music from Namco video-games, with Xevious as its centerpiece. A follow-up 12" single featured in its liner notes an entire science-fiction short story by Endō, set in the world of Xevious, with even a rudimentary fictional language. The theme music from Xevious was used during certain segments of the video arcade game-based television game show Starcade.

According to Namco Museum DS, a three-part novel was written about Xevious entitled "Fardraut". However, not much is known about the book, implying that it was never even released. According to the game, some backgrounds, characters, events and even sounds were inspired by the book.

Xevious has recently been resurrected as a comic strip as part of the ShiftyLook series of internet comic strips. The strip features a storyline focusing on a young pilot who breaks up with his girlfriend to fight the Xevious only to have her join the airforce alongside him afterward to save Nelvana.

There were several arcade sequels and a spin-off, though none achieved much popularity:

• Super Xevious (1984) was practically the same game made significantly harder, and with a few rarely-seen new enemies.
• Solvalou (1991) presented the same game with a pilot's-eye view. The game used 3-D flat shaded polygon graphics. Released in Japan only.
• Xevious 3D/G (1995) was an update on the classic with 3-D texture mapped polygon graphics and a simultaneous two-player feature. Released in Japan only.
• Xevious Arrangement (1995) was part of the Namco Classic Collection Vol. 1 game collection (along with the original Xevious and Super Xevious). The arranged version had improved music and graphics and different levels.
• Grobda (1984) was a spin-off starring an enemy character—the tank with corkscrew treads.

Four new versions were released for home systems (most of them being Japan-only):

• Super Xevious: GAMP no Nazo (1986) was released for the Nintendo Famicom and the Nintendo Vs. series on the Arcades. You must solve riddles in each stage in order to progress. Unless you meet certain criteria the stage loops indefinitely, getting harder and harder in the process.
• Xevious: Fardraut Saga (1988) was released for the MSX2 computers and developed by Compile. You can select between two modes at the title screen, Recon (port of the original arcade Xevious) and Scramble, which is a new 16-area game with new enemies and 4 different ships to play with (Solvalou, Solgrado, Zeodalley and Gampmission).
• Xevious: Fardraut Densetsu (1990) was released for the PC Engine and also developed by Compile. This is the sequel to Fardraut Saga and it features two modes of play selectable from the title screen, Original (port of the original arcade Xevious) and Fardraut, which is a 4-stage story mode with cut-scenes, power-ups and a different ship on each level.
• Xevious Resurrection (2009) is part of the PlayStation 3 downloadable title Namco Museum Essentials (Namco Museum.comm in Japan).
• An RTS game titled New Space Order, was in production in Japan by Namco Bandai Games but has been cancelled. It would contain elements from the Xevious video game series. In the game there was going to be an interplanetary nation called the "Military Empire," in which the population speaks the Xevi language, the same language spoken by the dwellers of planet Xevious. Their theme song, sung in Xevi, can be downloaded from the game's homepage.

Xevious has been ported to multiple other formats, including the Atari 7800, Atari 8-bit, NEC PC Engine, and Nintendo Entertainment System game consoles, as well as the MSX, ZX Spectrum, Commodore 64, Amstrad CPC, Apple II and Atari ST home computers.

The game has also been included in a number of classic arcade game compilations for consoles and PC, including Namco Museum Volume 2 for the original PlayStation in 1996, Microsoft Revenge of Arcade for PC in 1998, Namco Museum 50th Anniversary for Xbox, PlayStation 2, Nintendo GameCube, and PC in 2005 (The game did not appear in the scaled-down Game Boy Advance version of Namco Museum 50th Anniversary.), Namco Museum Battle Collection for the PlayStation Portable in 2005, Namco Museum DS for the Nintendo DS in 2007, Namco Museum Remix for the Wii in 2007, and Namco Museum Essentials for the PlayStation 3 in 2009. In 2004, Xevious was also ported to the plug-n-play format as part of the Ms. Pac-Man TV Game arcade compilation, released by Jakks Pacific and developed by HotGen Studios.

The NES version of the game was repackaged for Game Boy Advance in 2004 as part of the Classic NES Series, was included as an unlockable bonus game in Star Fox: Assault in 2005, and was released for the Virtual Console on January 15, 2007.

In 2005, Namco released the game on the mobile platform for cellphones. It was released on Xbox Live Arcade on May 23, 2007.

Paired releases with Super Xevious include Namco Classic Collection Vol. 1, Namco Museum DS and Xevious 3D/G+ for the original PlayStation.

An Atari 2600 port was planned, but never released.

This game has also been released as part of the Pac-Man's Arcade Party arcade machine in 2010.

3D Classics: Xevious is a port of this game with 3D effects added to separate all of the objects in the air and everything on ground, and the port takes advantage of the whole 3DS's top screen instead of it being limited to the game's original resolution (with moving clouds added on to the sides), it's available for download on the Nintendo eShop of the Nintendo 3DS console for $5.99.

Bootleg version

The arcade game Xevios is a bootleg version of Xevious.

The title graphic in the form a graphic representation of the name has been shortened rather crudely by removing the vertical slice of the graphic that contains the letter "U". The cut is evident in the multi-color graphic where there are some discontinuities in the graphic.

The placement of both the multi-color graphic and the yellow graphic have not been changed, so each are no longer centered.

The copyright notice was changed by the replacement of the "(C) (P) 1982 NAMCO LTD." string with "(C) 1980 WATSON CO.", and the removal of the red Namco logo underneath.

The Watson date is obviously wrong, since the clone cannot have been made prior to Namco releasing the game.

The bootlegger failed to remove the trick for generating a message right at the beginning of the game. As soon as Solvalou (player's ship) appears, move to the far right edge of the screen and begin bombing constantly. Continue bombing until the first set of attacking rings is very close to you and then shoot the rings. The message "DEAD COPY MAKING, copy under NAMCO program" will appear on the screen, as proof of the copyright violation.

The explosion sound is also different from the original Xevious machine.

In the Atari age, programmers used to hide in-game secret messages (the term "Easter Egg" was coined then) to get some much-deserved credit for their work, which otherwise would have gone just to the manufacturer. Xevious was among the first games to place hidden secrets or "Easter Eggs" in the game without any hints throughout the game. This includes multiple ancient-looking silverish towers in game, placed randomly underground. For example, on the right side of the map after the 1st river but before the three trucks/tanks/machines, move your target-guilder around until you see it blinking with an enemy for your bomber. Then fire some bombs in the tower. Bombard the tower again to destroy it and gain more points.

Just another hidden secret is the arcade-famous White Flag. To find the White Flag bombard the second river with grenades on the middle/left side and you will find one of the White Flags; move over it to gain a life. Right at the beginning of the game, go to the far right and fire your blaster to reveal the hidden message "NAMCO ORIGINAL program by EVEZOO". Doing the same trick in Super Xevious will bring on the screen "Special thanks for you by game designer EVEZOO". There are structures called "Sol Citadels" hidden throughout the game. The targeting sight will briefly flash red whenever it is over one of these structures. Dropping a bomb at that spot will first uncover the silo-like object (worth 1000 points) and dropping another bomb on it will award another 1000 points. There are also four special flags hidden at certain points in the game. Uncovering and flying over a special flag will award an extra life. The targeting sight will not flash when it is over a hidden flag. The special flags are in areas 1, 3, 5, and 7.

The names appearing by default in the Japanese version's high-score list are pseudonyms of the game designers and music composers. The North American version only allowed three characters for high-score names.

The Zapper and Blaster buttons were reversed between the Japanese and North American arcade versions.

There are several references to Xevious in Ridge Racer. Two bonus cars have this game as a sponsor, a red car, "RT Xevious Red" and a green car, "RT Xevious Green". They were used in the PlayStation version of Ridge Racer, Ridge Racer Revolution, and Ridge Racer 64. In R4: Ridge Racer Type 4 and Ridge Racer 64, a racing team has this game as a sponsor, donning a silver with blue stripes paint scheme, as well as their racing number, 02. The team is named "RT Solvalou", and they are a "hard" team, while in Ridge Racer 64, "RT Solvalou" is one of the four cars the player starts with. Ridge Racer 7, for the PlayStation 3, features a playable version of this game during the opening sequence. Players are given two lives in order to reach a pre-set high score. The full Xevious game is unlockable through completing part of the single player, offline Ridge Racer grand prix and UFRA circuits.

In Ridge Racer 3D one of the unlockable cars is the Solvalou, piloted by Pac-Man with sheonite shaped objects in front.

• In Star Fox: Assault, which was co-developed by Namco, the Special Flags are hidden secrets in the game's stages. The pickup sound for the flag is exactly the same as that in Xevious. Additionally, the NES version of Xevious is unlockable if the player earns every silver medal in the game.
• In Tales of Symphonia, which was developed by Namco, there is an enemy called "Bacura," which is one of the invincible flying panels from Xevious. It only appears at one point in the game, and has a very high defense, making it hard to defeat.
• In both Mario Kart Arcade GP and Mario Kart Arcade GP 2, arcade versions (co-developed by Namco) of Nintendo's popular Mario Kart series of games, Pac-Man appears as a playable character. One of his selectable karts is the Solvalou spacecraft.
• In EarthBound, music from Xevious can be heard in the background noise at the Onett arcade.
• Although not a reference within a video game, the Solvalou ship is available as an avatar on the PlayStation Network.