1) Omniverse is an NVidia "world" of rendering and creation that requires a high end NVidia card to use.  The plugin in iClone will allow you to move items/scenes from iClone into that world.  But not without a TON of difficulties.  I would NOT recommend any but the very experienced to go there (I tried and failed miserably and I'm kind of an expert in most things :>).

2) Popcorn FX is a particle system - particles are used for things like water, fireworks, sparks, fog, etc.  They provide a lot of atmosphere and if you need them there really isn't any substitute.  If you don't, you don't (and you will know if you need them - if you are trying to do something that requires particles).

3) iRay is another rendering system.  iClone itself has a native render, but iRay is just another way of rendering that some folks love, some hate.  You wouldn't need it.

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Alienware Aurora R16, Win 11, i9-149000KF, 3.20GHz CPU, 64GB RAM, RTX 4090 (24GB), Samsung 870 Pro 8TB, Gen3 MVNe M-2 SSD, 4TBx2, 39" Alienware Widescreen Monitor
Mike "ex-genius" Kelley