After having graduated from the University of Surrey with a degree in Computing and ICT, Masters started in the games industry as a tester with Simis Limited between May 1997 and November 1998, where he tested five products. Later, when the company was assimilated into Kuju Entertainment, he moved on and became a Games Designer with Kuju between November 1998 and April 2005.
After starting off in the United Kingdom, Steven traveled to Canada in 2005 to join Ubisoft Montreal, where he worked on Rainbow Six: Vegas as an AI Designer. After releasing the multi-award winning title, he joined the Assassin's Creed team, this time specializing in the Action Loop.
After completing that project, Masters decided to take a brief leave of absence, but returned to work on Tom Clancy's Rainbow Six: Vegas 2 during the closing stages of its development.
Following this, Masters became the Lead Game Designer on Splinter Cell Conviction, helping to manage a team of designers to deliver the game. After that, he rejoined the Assassin's Creed team in 2010 to deliver Assassin's Creed: Brotherhood as the Lead Game Designer.
- Team Apache (1998) - Mindscape
- Tank Racer (1999) - Grolier Interactive
- Peacemaker: Protect, Search & Destroy (1999) - Brightstar Entertainment
- Ka-52 Team Alligator (2000) - GT Interactive Software
- Fireblade (2002) - Midway Games
- Warhammer 40,000: Fire Warrior (2003) - THQ
- Tom Clancy's Rainbow Six: Vegas (2006) - Ubisoft
- Terror Strike (2006) - Konami of Europe
- Assassin's Creed (2007) - Ubisoft
- Tom Clancy's Rainbow Six: Vegas 2 (2008) - Ubisoft
- Assassin's Creed - Director's Cut Edition (2008) - Ubisoft
- Tom Clancy's Splinter Cell: Conviction (2010) - Ubisoft
- Assassin's Creed: Brotherhood (2011) - Ubisoft
- Assassin's Creed III (2012) - Ubisoft