Sega began to release more "Sonic" games for mobile phones, such as iOS and Android devices. After he developed a version of "Sonic CD" for modern consoles in 2011, Australian programmer Christian "Taxman" Whitehead collaborated with fellow "Sonic" fandom member Simon "Stealth" Thomley to develop remasters of the original "Sonic the Hedgehog" and "Sonic the Hedgehog 2" for iOS and Android, which were released in 2013. The remasters were developed using Whitehead's Retro Engine, an engine tailored for 2D projects, and received praise. "Sonic Dash" (2013), a "Temple Run"-style endless runner, was developed by Hardlight and downloaded over 350 million times by 2020, and received a in 2015. Sonic Team released "Sonic Runners", its first game for mobile devices, in 2015. "Sonic Runners" was also an endless runner, but was unsuccessful and discontinued a year after release. Gameloft released a sequel, "Sonic Runners Adventure", in 2017 to generally positive reviews.