Add'It

Add'It is an 8 oscillator additive toy with 4 typical waveforms and a dual SVF multimode filter. Takes advantage of its modulation capabilities segmented in.

A - Amplitude
P - Pitch
B - Stereo balance.

Too few preset programmed, but they sound different compared to any other MVX stuff thanks to the added layers that provide extra timbres that can be dynamically modulated with each of its 3 LFO & 3 ADSR.
It is not intended to create just typical additive stuff like Drawbars or typical organs. The modulated parameters gives a chance to create unique sounds to leave behind the limitations of the subtractive synthesis.

Of course, you'll need this Microsoft runtime or Synthedit 1.0+ to be installed in your system to see it's bizarre GUI, but its low memory requirements (less than 30MB) won't eat your resources. CPU usage is also small for nowadays systems as it was initially developed in a Core 2 Duo CPU.