Part of the beauty of the game of chess is that each possible unique geometric pattern of movement is accounted for exactly once by each piece. Mixing and matching new random patterns that don't make logical sense on their own is no longer chess, it's a completely different game. Simply extending it a dimension is extremely complex but not sheer lunacy lol. Pieces, rules, and even board size is the same, just in a higher dimension, it's a good exercise visualizing in 3d. Alot of other games could also be scaled up to 3d for added complexity, like connect 4, mazes, that tron light cycle game, that unblock me game where you have to slide blocks around to free up one...etc, all of these would be much more fascinating in 6 possible directions instead of 4.
Anything other than cubic chess 8x8x8 board ain't real 3 dimensional chess!
I thought I’ve already seen the most ridiculous variant ever. I was wrong. 512 squares with 256 being occupied is the new, best, winner of the most outstanding representation of sheer lunacy I’ve ever encountered.
You obviously have never heard of Taikyoku Shogi. And before you ask: yes, a complete game of that was actually played ( https://www.youtube.com/watch?v=_c0Y26iTPSM , game starts at 2 : 30 min, after a Japanese introduction )