Nekobee is a realtime, velocity-sensitive bass synth DSSI-plugin for linux, originally developed by Nekosynth.co.uk. There is another version created by the Distrho team, with newer GUI and animated kitty :) renamed "Nekobi," and is included in the KXStudio repositories.
Nekobee is a single-oscialltor synth that provides a rich, punchy timbre typical of bass synths. Waveform choice is square or saw, fine-detunable up or down one octave. As Nekobee is monophonic, it's also useful for leads, like in the "Rezouu" demo above. The cutoff and resonance are sensitive and expressive. "Env Mod" is hard-wired to the modulation wheel, and adjusts the filter depth, as in the "LazerSynth2WithEnvMod" demo. The Decay knob adjusts the filter decay (not amplitude) and the Accent knob gives some boost at some settings. The "Classic Synth 1" demo was done modulating the Decay knob.
Hopefully some additional sonic control features such as portamento and pulse width modulation for the square wave (for pulse!) will be added in the near future. Who knows...
The "original" Nekobee at Github
Distrho's Nekobi at Github