Here is (far too much) detail on that:

It depends on which bit of my software I'm playing with.  The most musically satisfying bits are the ones I've preprepared.  In that video, the first section (Tritone) I've set up one key selecting which of the patterns (each of which are single chords that pitchbend to other chords), and another couple of keys which I'll use simultaneously to modify this - whether I want just the first frame of the pattern looping (keeping the original chord), whether I want to return to the start of the pattern, or to step through the pattern.

The next bit, (spectrum on my left), is a set of preprepared PlipPlop patterns, that are chained by holding different keys though the transitions (no key press and the pattern loops).

Then some 'one shot' QChan patterns (spectrum on my right), that wait for a keypress than play them to completions (generally I've got these set up as chords or quick arpeggios of various lengths and types).

Then I use my 'uglisynth' (right hand spectrum again) which is a (nearly chromatic) set of notes I can play like a incredibly un-intuitively laid out piano - I use both hands for this.  (This engine was *horrible* to tune the notes, but I do like the sound of it).  On the video I continue to play this synth (very conservatively) with might right hand, whilst I change Plip Plop patterns with my left hand on the other spectrum.  My left/right hand independence needs work, it turns out!

Then right at the end of the piece (the Manic Miner descending boot type sound) is where I switch to a little beep synth I've made. This is actually a chromatic piano style synth with up to three keys at once that it quickly arpeggiates through, however here I'm just using it here because it has an extra keypress that changes the pitch of one of the otherwise unused keys on the fly.  I was using this to 'hand tune' notes, but realised it was quite good fun as an effect.

I've not really 'got' the way of performing with all of the synths/engines yet (there are a few others I've been hacking at too).  I'm hoping my muscle memory will catch up before I perform with an audience!

The most original thing I've seen done with 1-bit ZX Beeper for a long time!

Love the qchan bits.

So was it a completely new 'live performance' engine or pre made sections/chords played on certain key presses ?

Once I've done a 'gig' I've been asked to do next month (it's quite an arty art-music venue, rather than a nightclub), I'll post my [horribly dirty] code here, and people can do something better with it.  At the moment it's evolving on a day by day basis, as I'm writing more music.

Anyway, I filmed a quick snippet yesterday:  https://youtu.be/cQcWz4JG-yk

Thought y'all might be interested.