Question: Arcadians is a fixed shooter for the BBC Micro and Acorn Electron, and is very similar to which arcade game that was developed by Namco and released in October 1979?

Context paragraphs:
The Micro User: The Micro User (titled BBC Micro User in the first three issues) was a British specialist magazine catering to users of the BBC Microcomputer series, Acorn Electron, Acorn Archimedes and, to a limited extent, the Cambridge Z88.  It had a comprehensive mix of reviews of games, application software, and the latest Acorn computers; type-in programs (duplicated on a "cover disk" which was available separately), a correspondence page offering help with computer problems, and approachable technical articles on programming and the BBC Micro's internals.

Galaforce: Galaforce is a fixed shooter video game for the BBC Micro and Acorn Electron, written by Kevin Edwards and published by Superior Software in 1986.  It spawned a sequel, "Galaforce 2" (1988) and an updated remake for Microsoft Windows, "Galaforce Worlds" (2003).

Confuzion: Confuzion is a puzzle game developed and published by Incentive Software for the ZX Spectrum, Commodore 64, BBC Micro, and Acorn Electron.  The object is to guide a spark along a fuse wire.  It is similar to the 1982 arcade game "Loco-Motion."  "Confuzion" was written by Paul Shirley who later wrote "Spindizzy".

Acorn Computers: Acorn Computers Ltd. was a British computer company established in Cambridge, England, in 1978.  The company produced a number of computers which were especially popular in the UK, including the Acorn Electron and the Acorn Archimedes.  Acorn's BBC Micro computer dominated the UK educational computer market during the 1980s.  It is more known for its BBC Micro model B computer than for its other products.

Snapper (video game): Snapper is a clone of the Namco arcade game "Pac-Man" programmed by Jonathan Griffiths for the BBC Micro and released as one of the launch titles for Acornsoft in 1982.  It was later released as one of Acornsoft's launch titles for the Acorn Electron in 1983.

Galaxian: Galaxian (ギャラクシアン , Gyarakushian ) is an arcade game that was developed by Namco and released in October 1979.  It was published by Namco in Japan and imported to North America by Midway that December.  A fixed shooter game in which the player controls a spaceship at the bottom of the screen, and shoots enemies descending in various directions, it was designed to compete with Taito Corporation's successful earlier game "Space Invaders" (which was released in the previous year, and also imported to the US by Midway Games).

Starship Command: Acornsoft's Starship Command is a computer game released in 1983 for the BBC Micro and Acorn Electron.  It was available on cassette as well as 5.25" disc for the BBC and ROM cartridge for the Acorn Electron Plus 1 expansion module.  The game was written by Peter Irvin who, along with Jeremy Smith, went on to create the complex arcade adventure "Exile".

Acornsoft: Acornsoft was the software arm of Acorn Computers, and a major publisher of software for the BBC Micro and Acorn Electron.  As well as games, it also produced a large number of educational titles, extra computer languages and business and utility packages – these included word processor "VIEW" and the spreadsheet "ViewSheet" supplied on ROM and cartridge for the BBC Micro/Acorn Electron and included as standard in the BBC Master and Acorn Business Computer.

Cybertron Mission: Cybertron Mission is a two-dimensional shooter game, released by Micro Power (a.k.a. Program Power) in 1983 for the BBC Micro and Acorn Electron and later ported to the Commodore 64 in the same year.  The game is heavily influenced by the 1982 Atari 8-bit computer game "Shamus", which was itself inspired by the 1980 arcade game "Berzerk".

Arcadians (video game): Arcadians is a fixed shooter for the BBC Micro and Acorn Electron programmed by Nick Pelling and released by Acornsoft.  It is very similar to the Namco arcade game "Galaxian".

Supporting paragraphs: Arcadians (video game) Galaxian
Answer: Galaxian