SuperTron is a free virtual analog synthesizer VST instrument that generates sequences typical of the 70s and 80s, Dance, Trance, percussion, analog strings and other retro sounds.
Sonico is a free VST synthesizer with analog – retro “features”: mono keyboard, mono output, no velocity.
BasicBat is a free FM VST synth instrument for creation and emulation of acoustic and electronic basic drum set: bass drum, snare and Hi Hat.
Crio is a free virtual analog / FM synthesizer to make arpeggios, bass, solos, leads, FX-style sounds. The aim was to make an instrument with minimal controls and maximum functionality, to be used at studio or live, with facilities to drastically modify the sounds on the fly, while playing.
Patagon is a free virtual FM – Analog VST Synthesizer instrument with step modulator. It´s make electronic arpeggios, pads, acoustic instruments, etc…
EmulTuition is a free VST instrument FM (to Oscillators and Filters) and Subtractive Synthesizer.