Hi,
If you prefer something of Menu-diving instead of combination of buttons-colors... you have https://www.modulargrid.net/e/xaoc-devices-zadar instead Quadrax
-- ferranadsr

Indeed Zadar is often categorized as EG but I'd argue it's more of a complex shape LFO than an EG one can use to control the amplification section of a voice. You can do it, but it's not a great interface for it, something like Quadrax, Nano Quart, or even Maths offer better interfaces to play with the volume envelope. I personally found Zadar annoying as a classic EG, having both Quadrax and Maths at hand... But as an LFO, it's quite unique !

You can use a second-hand Quadra instead of Quadrax, or something like Nano Modules Quart.
-- dubstepjoris

Sure Quadrax is capable of being complex but it doesn't have to be if you don't go into the menus, in fact I used mine as a simple Quadra for a (shamefuly long) while before finding time to dig in (worth the hours, for sure). With the experience I have now in Euro (a few years), I'd say that's one of the modules I will never sell, it does so much and it does it really well.
In my mind, it's a bit like buying a Maths: it's something a newcomer has very little chance of using to its full powers, but that will become useful to almost any synthesist out there once experience grows. Maths is perhaps a better teacher because it can do more different things and also because there are quite a few learning resources available for it.

Looking at the rack, I find the Quadrax and its versatility would be one of the most important modules that make the rack "interesting" for me as it covers more EG, but also linked envelopes, waveshaping synced LFO's etc. For the type of music you mention, that will come in very handy as I suspect the O&C will be forever busy with something else...
In fact, I'd even say that for the music you want to make, Quadrax + Zadar would be ll you need forever. If you would consider another voice (Odessa is HUGE for this type of rack), you could free up some space for it. That free HPs game is one you'll have to play a bit with this size of rack.

All the best for your project !

--- Voltage control all the things ---