VST Zone has released Strum, a freeware Karplus-Strong synthesizer instrument written completely in assembly.
Two different and independent string generators for more variety of sounds, with own feedback, string length, attack/decay envelope and vibrato settings. First OSC is trying to simulate basic characteristics of four basic string types – nylon, bronze, steel and flatwound. Second generator uses basic shapes – sine, saw, triangle and square with additional options to tweak (tension & position).
Both generators share the same amp envelope, tremolo, timbre feedback settings and multi mode filter (lowpass, bandpass, highpass, bandreject, peak, Chamberlin lowpass, bandpass, highpass, peak, zOne lowpass, bandpass, highpass, peak, 303 lowpass, highpass and resonant filter). One LFO for cutoff modulation with 17 different shapes (Sine, Saw, Triangle, Ramp, Square and 4 of each based on Lorenz, Rosler and Ikeda attractors.
Delay, chorus and reverb module and simple soft knee limiter.
Strum for Windows (VST) is available to download from KVR Audio as part of the Developer Challenge 2014 contest.