Delta hosts seven other people's emulator cores behind a seven day install clock

Seven systems, seven borrowed cores, Genesis still in beta

The supported list is explicit: Nintendo Entertainment System, Super Nintendo Entertainment System, Nintendo 64, Game Boy and Game Boy Color, Game Boy Advance, Nintendo DS, and Sega Genesis / Mega Drive marked in beta. Underneath each one the README names a core it did not write. NES runs on Nestopia, SNES on Snes9x, N64 on mupen64plus, GBC on Gambatte, GBA on visualboyadvance-m, DS on melonDS, GEN on Genesis Plus GX. That is the architectural decision stated in a single line: Delta is a shell that hosts other people's emulation, and the claim of accurate, full speed emulation is credited to those cores rather than earned here. The contrast with the project's own ancestor is sharp. Delta is described as the spiritual successor to GBA4iOS, a Game Boy Advance emulator the author and Paul Thorsen wrote together in high school, rebuilt from the ground up with modern iOS features and more systems. The application is Swift. The emulation is not. Adding a system means finding a core to wrap, not writing an emulator.

Every Delta Core lives in its own repository, wired in as a submodule

Delta was designed to be modular from the beginning, and the layout proves it. Each Delta Core has its own GitHub repository and is added as a submodule to the main project, which is why .gitmodules and a Cores/ directory sit at the top level next to Delta.xcodeproj/, Delta.xcworkspace/, Delta/, DeltaFeatures/, DeltaPreviews/, External/, Systems/, Resources/, Artwork/ and Docs/. The division of labour is spelled out. This repository is just a regular sandboxed iOS application holding the storyboards, app specific view controllers and database logic. DeltaCore is the middle-man between the high level app code and the specific emulation cores, and it is where emulation, controller skins, save states and cheat codes are reached from; the README expects other emulator apps to build on that framework too. Delta also uses Roxas and Harmony, which the README calls the author's own private frameworks for sharing common functionality between his apps; Roxas is linked to its own GitHub repository.

Apple declined the App Store, so the author built the installer

Delta was originally developed under the impression Apple would let it into the App Store. Apple later changed its mind, and the author's response was to build AltStore, which the README now calls the official way to install Delta. Emulator and installer are one product from one author, which is worth knowing before you judge either. It also puts a clock inside the install path. Once Delta is on the device through AltStore you must refresh it at least once every 7 days or it expires and needs installing again. AltStore attempts those refreshes in the background when the device is on the same WiFi as AltServer, and a Refresh All control forces them by hand. The same paragraph says AltStore tells you when a new update is released, so upgrading Delta happens inside AltStore rather than inside Delta.

Five steps, one button labelled FREE, and no command to copy

The installation section has no command line. Installation runs through AltStore in five steps. Download AltServer for Mac or PC from https://altstore.io. Connect the iOS device to your computer with a lightning cable, or USB-C for iPads. Follow the instructions at altstore.io/faq to install AltStore onto the device with AltServer. Open AltStore on the device and navigate to the Browse tab. Find Delta and press the FREE button, which starts installing the app. What you can copy instead is the tree you should end up with, including the submodule wiring and the vendored CocoaPods, since Podfile, Podfile.lock and a populated Pods/ directory are part of the checkout rather than something a build step fetches for you:

.gitmodules
Artwork/
Cores/
Delta.xcodeproj/
Delta.xcworkspace/
Delta/
DeltaFeatures/
DeltaPreviews/
Docs/
External/
Podfile
Podfile.lock
Pods/
Resources/
Systems/

Sideloading the .ipa is the other route and it costs you updates

The page offers a second path: download the compiled `.ipa` files from Releases and sideload them with whatever sideloading method you prefer. The cost is named in the same paragraph. You will not receive automatic updates, and Delta has to be updated manually by re-sideloading each new version. So the real decision is between a maintenance ritual that hands you in-app updates and a manual install you fully control. Neither path removes the versioning question, because the newest tag is v1.6 from 2024-07-11, with v1.5 from 2024-02-01 and v1.4 from 2023-02-28 behind it, while the last push to this repository landed on 2026-10-24. A build taken from Releases can therefore be more than a year behind the source.

Save states carry locks, backups and one button, but Quick Saves need hardware

The save state handling is the most defensive corner of the feature list. You can save and load states for any game from the pause menu, lock a state so it cannot be accidentally overwritten, and rely on automatic backup states so progress is not lost. A second tier exists for the ones you touch constantly: Quick Saves, which can be saved or loaded with a single button press, and the README attaches a condition, an external controller. Fast forwarding follows the same pattern, toggleable from the pause menu or bound to a mapped button on that controller. Hold Button attacks the opposite problem by choosing buttons for Delta to hold down for you, with the README's own examples being the run button in Mario games and the A button in Mario Kart. Mappings are customizable per system and per controller, so a PS5 pad and an Xbox Series X pad do not have to share one layout. Bluetooth and wired keyboards and the Apple Smart Keyboard are supported too.

Delta Sync carries cheats and skins, while the hardware support has hard edges

Delta Sync is the least emulator-shaped feature and the one with the widest reach. It syncs games, game saves, save states, cheats, controller skins and controller mappings between devices, keeps a version history of everything it syncs, and lets you restore earlier versions. Two cloud back ends are supported, one of them Dropbox. Cheat support is enumerated per system and named by device: Game Genie for NES, SNES and GBC, GameShark for N64, GBC and GBA, Pro Action Replay for SNES, Action Replay for GBA and DS, Code Breaker for GBA. Peripheral support is narrower, and the README marks the limits plainly: gyroscope support for WarioWare: Twisted! only, microphone support for DS only. Hardware controllers are named too, PS4, PS5, Xbox One S, Xbox Series X and MFi, alongside bluetooth and wired keyboards and the Apple Smart Keyboard. Tapping the screen with 3D or Haptic Touch peeks at games, states and cheat codes, and app icon shortcuts jump back to recently played titles. One of the seven systems remains flagged beta.

Editorial conclusion

Delta fits an iOS user with AltStore already set up who wants one native app covering several classic systems, accurate cores and save states with backups, and who will keep it refreshed at least once every 7 days. It does not fit someone who wants automatic updates without going through AltStore, someone who needs Genesis support today, or someone who wants to build without pulling submodules and vendored pods. Verify three things before you commit: that AltStore can reach your device for the 7 day refresh, whether the build you install is v1.6 from 2024-07-11 or something newer, and whether the systems you actually play are on the supported list or still in beta.

Frequently asked questions

Official sources

1. Issues
2. License: AGPL-3.0
3. README
4. Releases
5. rileytestut/Delta on GitHub