Just as Strymon's Flint combined tremolo and reverb in a pedal, there are three types of tremolo available here.
The Normal setting is an optical-style tremolo that's based on a 1967 Fender Vibrolux. The Harmonic setting has a phase-y sound as found in Fender's early 1960s 'brownface' amps.
The Bias tremolo offers more of a dirty pulsing sound, if you're looking for the sort of trem heard from a Vox AC30.
All three sound excellent and offer variation via the Speed and Depth knobs, but if you want to move away from 'amp tremolo' sounds, the Shape knob offers waveform shaping with a typical sine wave at its central position, running to square wave and sawtooth at the two extremes of its travel.
The Neuro app can take things more 'out there' with alternative algorithms, including filtered tremolo, tremolo mixed with chorus, or flanger and odd sequenced effects.