Even with their game established, Sidhu and Rothstein faced internal challenges at PopCap to increase the level of interactivity with the game, but the two defended their vision of the game. Once the team had established the core mechanics of the game, they brought on character artist Walter Wilson, background artist Marcia Broderick and an additional coder, Eric Tams, to help complete Peggle within its two-year development period. They found over time that a static field of pegs provided a more enjoyable experience for the player the path of the ball would be more predictable, leading to the gameplay mechanic of requiring only a random subset of orange pegs to be cleared. The team initially incorporated a "rapid-fire" mechanic used in pachinko, along with numerous moving targets, but they found this made the levels either too fast-paced or too demanding of the player. Initial designs focused on bringing together elements of pachinko with Breakout. After seeing a 2D game engine created by PopCap programmer Brian Rothstein, Sidhu was able to realize his game, and worked with Rothstein for the first five months of its development before bringing in additional programmers. However, he recognized that pachinko was mostly luck-based, and would not translate well into a video game. Peggle was originally envisioned by PopCap's studio director, Sukhbir Sidhu, who was inspired by pachinko machines. The Peggle franchise has been downloaded more than 50 million times. Spin-off games include Peggle Extreme (2007) and Peggle World of Warcraft Edition (2009). Peggle was released initially for desktop in 2007, followed by three sequels: Peggle Nights (2008), Peggle 2 (2013), and Peggle Blast (2014). Peggle is an American series of casual puzzle video games created by PopCap Games. JSTOR ( November 2018) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.