Users were able to get GBA4iOS onto their iOS device without jailbreaking it by setting the iPhone's date back to 2012, but even a 2.0 update to the software made it easier to install the emulator and removed that requirement. A built-in web browser allowed users to install and play original Game Boy, Game Boy Advance, and Game Boy Color ROMs right on their iPhone or iPad. Although the platform has yet to be confirmed, Testut's mention of GBA4iOS alongside the Delta teaser suggests that the new emulator will be for iOS devices.
The new website for Delta doesn't confirm how the emulator will handle downloads yet, but will likely be in a similar vein to Testut's previous software emulators. Responding to a few user questions in the original Twitter thread, Testut mentioned that tvOS support is something he wants, but "there are some technical issues right now standing in the way," so the launch is expected to focus on iOS.
Goodbye GBA4iOS. Hello, Delta. https://t.co/If4W92MMmf— Riley Testut (@rileytestut) November 21, 2016