Delta represents a significant evolution in mobile emulation software, building upon the foundation of developer Testut Tech's previous GBA4iOS project. This iOS-exclusive application provides comprehensive support for multiple Nintendo gaming systems, positioning itself as a premier solution for retro gaming enthusiasts on Apple's mobile platform. The emulator operates within Apple's developer guidelines while delivering robust functionality for legitimate game preservation and play. The application's core functionality spans seven major gaming systems including NES, SNES, Nintendo 64, Game Boy, Game Boy Color, Game Boy Advance, and Nintendo DS. Each system features accurate emulation with customizable control schemes, save state functionality, and cheat code support. The Nintendo DS implementation stands out with unique dual-screen interface adaptation and online multiplayer capabilities for compatible titles, enabling cross-device gameplay sessions. File management operates through iOS's native document picker system, allowing users to import legally obtained ROM files from cloud storage services or local directories. User experience demonstrates thoughtful design with context-aware control overlays that automatically adapt to each gaming system's original controller layout. The interface maintains consistency across different devices, with particular optimization for both iPhone and iPad screen sizes. Real-world usage patterns show most users employ the application for portable retro gaming sessions, with save states enabling convenient play during short breaks or commutes. The application's background audio handling allows seamless switching between games and other iOS functionalities without progress loss. User feedback trends indicate overwhelmingly positive reception, with particular praise for the application's accessibility and reliability. User DannyKuhlmeier noted on August 28, 2025: 'Love this app it's so easy to add my favorite Nintendo games and play them.' Another user, Loristril, mentioned on August 24, 2025: 'The issues I had before are fixed - DS doesn't have the black lines thing anymore and the overlay is nice.' Multiple reviews highlight successful operation on older hardware including iPod Touch devices, as noted by Brit_guy101 on August 29, 2025. The application demonstrates notable strengths in its multi-system support and polished interface, though limitations include the absence of PlayStation-era console emulation that some users have requested. Legal considerations require users to provide their own game files, which may present acquisition challenges for less technically inclined users. Ideal use cases involve retro gaming enthusiasts seeking a unified solution for Nintendo's classic portable and console libraries, particularly those valuing online multiplayer functionality for Nintendo DS titles.