I have no idea what Deeproot are working on but my best guest (based on Pinball's next logical progression) would be a mix of a real physical game and some virtual elements.
Andrew Heighway had an idea of using a screen overlay to cover the entire playfield on which images could be projected. We later developed this idea into using a virtual visor that the player would wear which could project in real time 3D, overlaid animations to a game of pinball. Very similar to what Pinball FX3 are doing now, but for real.
The visor idea is many years in the future but what I think Deeproot might be attempting is the full screen overlay which can project animations of explosions, sparks, smoke onto the playfield.
This isn't a new idea and I've been doing this myself in my own virtual games for nearly a decade - adding holographic animations to games like Medieval Madness (castle explosions) and Iron Man (lighting bolts).
But on a real table, it's never been done before.
Imagine a smoke bomb that obscures part of the playfield for a second or two, dropped by a player using a mobile app? The possibilities are endless.
It may be a tough sell to seasoned old farts, but the new generation will love it.
It's the next step in pinball's evolution. Only question is, who's going to get there first.