Relentless released its first self-published title, Blue Toad Murder Files on PC and PSN in 2009 and Quiz Climber Rivals, for iPhone in 2011.

Relentless Software was founded in 2003 by David Amor & Andrew Eades, who had previously worked together at the Brighton office of Computer Artworks.

[1] The company name arose from Amor & Eades ambition to develop video games in a different way to the perceived norms of the industry.

They wanted development to be a steady flow of work rather than the more normal cycle of a slow start leading to a project ending with long "crunch" periods.

They typed unstoppable into an online thesaurus and of the synonyms returned they chose Relentless as the company name.

In 2004 SCEE were approached by a company called SleepyDog who had secured the rights to a large number of music tracks and wanted Sony to use them as the basis of a quiz game.

[1] SCEE approached Relentless and asked them to design a quiz game using the music that Sleepydog had the rights for.

: The Schools Quiz - was developed in association with the UK Government's Department for Education and Skills (DfES), with the game's 5,000 questions being based on the Key Stage 2 Curriculum that covers children between the ages of 7 and 11 years.

The 1-4 player game leans towards TV murder mysteries with "witnesses, alibis [and] motives" rather than being a logic puzzle like Cluedo.

[12] As of July 2012, the game had sold over half a million copies, with the free episodes taking the downloaded total to 827,000.

[15] In May 2011 Relentless announced a deal with PlayJam to create content for their TV based gaming network.

[17] The second title Mutation Station is set in a mad scientist's lab and uses morphing of the Kinect video feed to transform players' appearances.