I don't think you
do still want it?
You want what it
represented and what it could show off, but the actual game and engine had limitations that likely would have been a drag in the long-term.
Deep Down showed itself off so well because it simple and allowed cool things to happen in semi-controlled environments. It was a corridor dungeon crawler with randomly-generated maps. Areas were boxy and replicated procedurally in the engine, with the one large dragon cavern fight space breaking away from the walled-in interior spaces (sometimes lit by outside light spilling in but usually a dark cavern with simple block arrangements.) It's doing a lot of things that other games have done (the
Panta Rhei wiki page summarizes a lot of its effects and techniques,) but because this was contained in a corridor and mostly kept in the dark, the effects could be controlled and optimized to show their best; had this been an open-world game with a game camera less constricted to the narrow player view in confined corridors, you would see its qualities in a less flattering light.
Combat, at least in the TGS model, was relatively rudimentary in terms of gamer expectations. The choice-based RPG mechanics were interesting as opposed to the more whittle-down approach, and there were context-sensitive action moments like the fake chests and the fire turrets which can be destroyed, plus the heavy attack sequences are reminiscent of some of the extremely weighty, measured attacks in Monster Hunter. Some people would have appreciated its slow and deliberate style (and the final game might have had more action-oriented combo technique than that seen in TGS?) but most would have found it dry and sluggish. And going by that dragon boss, the approach to big creatures was a war of attrition, a stick-and-move technique based on charging weapons as opposed to combo or fully dynamic combat. The dragon was basically a giant turret that spun around and fired flames at you to dodge or wall off.
Now, some people would have enjoyed a game like this, and maybe
you are among them. (I sure regret that the TGS demo never got out for everybody to play.) And the final game would have been more rich and complex in systems to play with than we saw in the 2014 play test. But Deep Down was going to be much more of a simple multiplayer dungeon crawler than people understood. It was not going to be a big, sprawling RPG epic as people imagined when they first saw that trailer. It was going to be a free-to-play multiplayer dungeon hack. Think more Wizardry than Skyrim, but with realtime fighting and co-op. (It also was going to have a weird alt-future storyline, sort of like AC where you in the future travel back in time to spelunk into caverns.) If that's for you, then I feel for your loss, but for most people, we probably got the better deal in Capcom putting its effort into Monster Hunter World and RE Engine games instead of continuing this project.