Pisscutter is a free VST synth for Windows.
Here's a audio/video demo that will let you decide just how cutting it is.
Pisscutter is similar to Casio’s CZ digital synths of the 1980s and is capable of producing a wide range of usable timbres with relatively few controls.
Whilst CZ synths relied solely on phase distortion to create sounds, Pisscutter also has a flexible filter section to enhance it’s potential. Low-Pass (12 or 24dB/Octave slope) and Band Reject (Notch) filters can be mixed in mono or, by using the new X-Pan feature, in a full stereo signal path.
A new Modulation Envelope features multiple interpolation methods and can be looped for long pads. There are two separate overdrives in the signal path and a single LFO is augmented by a couple of new modulation sources. The Sweeper is a specialised LFO and the Randomator (there are two of these) offers random variation to many settings, for a more human/natural feel (or craziness).
Demo video via myVST.
Affordable workstation type keyboard