This fully synthesized grove app has CoreMIDI clock and background audio support to work as a companion app with other apps such as Finger's Bassline. Updates have greatly improved the usability of this app. The synthesis is still kind of weird, offering their own unique control variables, but not with any consistency. Rimshot, for instance, is designed with just Tune, Drive, and Decay. Granted, this is more than you'd get on an 808, but with the many options on other elements this seems disappointing. All effects are global (with no ability to cancel it on individual parts). The interface design is well thought out though, with all parameters controlled by easy-to-use sliders, instead of finicky little knobs.