3 Dimensional Cubic Chess 8x8x8 Board

It's not working, can't sign in nor create an account. Email verification keeps going back to the same previous page.

This for Steam? As there are no such requirements for the game itself. It is hosted on steam tho and as such will require an account. 
https://store.steampowered.com/app/3463010/ChessFinity_Demo/ 
Is the direct link for the demo. But - as I say you still need to make a steam account if you do not have one. Their support are pretty solid tho, or so the memes say.

Yes I tried this so now I have a Steam account and I installed a Steam client and then I sill had to install your 700 Mb demo and then there was not much to see. Bit waste of my time actually.

What do you mean , ser? Not much to see? If there is a bug - do tell.

I tried to create an account. It keeps looping between email verification and then "signing in" even though there was no "create username/password" screen at any point. So I click don't have an account again and it goes back to email verification. Not sure what to do.

I created a new steam account to test it and yeah , steam seems to get hung up on the verification captcha. I simply closed the new account registration window and clicked on it again. It worked second time round. But its a bit different for me as I have 2FA via steam app - you would just verify you email - they send a 5 digit code. 
Hopefully it works for you. If you have some issues ; DM me , i guess.

Not what I said. I said it keeps looping between verifying email page and the sign-in page. Captcha works fine. Nothing ever comes up to enter info to create a new account.

I had a brief glitch with email verification, but after re-trying that worked. That is not the fault of @Justanaotherusername13, that's something with Steam itself.

LOL after diner I found out that somebody who I know and does gaming, is also on Steam. I myself don't do any gaming.

W.r.t. the ChessFinity demo, I tried to click through it, I saw nice 3D images with the promise that it would be possible to move them around, but beyond this I did not find any option to see or do something more substantial. Perhaps I was too impatient, perhaps I missed something important.

For lazy people like myself, maybe an introduction vid on Youtube would help. Perhaps it would make me think something like - aaah so I was supposed to click there and then there.

Fair enough , the UI / UX is not ideal ( will work on that ) 
I will make a video explainer later but here is a brief explainer:
You start on the Main menu where if you click the shiny PLAY button it expands to give two options , Join or create. For multiplayer you will paste your lobby code in this box and click join. When you create you will have 4 options ; Classic , Modded ( This is the 3d stuff that we want to test out ) , 4 player and Mana. They all have AI , solo or online ( except mana , im fixing that now ) - the online is better as the code is more robust and you can select different starting levels for your pieces layouts. 
Currently the King does not have the space verticals - as I felt it was OP but , we can have a play with both when I push a new version out. 

Nope still doing that same loop thing lol

Not sure. Are you on mac or PC or linux , do you use a VPN some sort of network obfuscation. 
When i tried it , the captcha was the thing that made it loop. I clicked it and it seemed like it worked but then it failed and told me to do it again. I would say the typical computer supporty type things: reinstall steam , restart your computer and try again. The username might have been taken or email might not be the type that steam supports - they didn't like my xyz domain , but we all have lots of email addresses.

Phone

OK I played a game in your demo. I checkmated your King by moving my Queen to the 3rd level and then giving check from exactly above your King. That tells me that the "AI" is not too strong.

I think the real challenges in 3d chess are humans. I can give you a game if you would care for it.
Indeed the "AI" is not something i have put much effort into. Do you think its something I should focus on? The issue is thinking time ; with all the extra positions to think about - currently it has a depth of 2 , any more and it would take around 3 minutes thinking per turn which ... well - you might not like. Currently around 30 seconds per move , give or take. 
The classic chess AI is pretty strong tho - 3300 max

Actually the real challenge is physically accessing the board! How do you get your hand inside a solid 8x8x8 cube to grab the pieces? And if the levels are spaced out by a few inches then it distorts perception of the piece movements. Has to be digital obviously, but even with that it would be extremely hard to "see" 3d diagonals and knight moves within such a cube lol

In #189 you said that "They all have AI" and that remark raised some expectations on my side. Your AI failed to see a very simple mate in 1 threat.

One other thing I noticed, when trying to make the board 8x8x8, some of the pieces went 'out of sight' of the visible board so to say, with no way for me to zoom out in order to see all of them.

I have numerous solutions to this:
1. You can manipulate the board visual settings 

The Y axis allows for vertical displacement and it looks like this after ( its also represented in the cube above.

Here is how it looks without it :

2. We can layer the boards in a more traditional way to allow for levels to be seen side by side :

3. We can select the pieces we want from a side menu :

4. There are quite a few coding tricks that limit you from being able to select a coordinate that you do not need to and keep the game rulebased. This isn't tabletop simulator it actually has chess as its baseline.

Sorry to disappoint - you are more than welcome to code a good engine for 3d chess for me.
The pieces went out of sight? Can you drop a screenshot in? 
I would check the tips out and go through the tutorial to check the controls. Press M while in game to change to 2d view or play with spacing settings.

I can't even code lol

in college I took 1 computer science course that was like an intro to Javascript and html, couldn't even figure out how to make a 4 function calculator. Ended up with like a C lol

Actually I've written a chess engine. But not a very good one when I consider how many great chess engines and chess programmers we have out there.
Still, my engine decently handles forced tactics at limited depth.
To extend this to 3-dimensional would in a way be straightforward. It already has configurability of piece movements, for 3D that's nice, as the exact piece movements in 3D are still open for discussion.
So yes, it would be doable in limited time, to create a 3D chess engine, that is exactly as annoyingly slow and positionally laughable as my current 2D chess engine already is.

But the visualization part would be a completely different topic. I asked some questions about this to ChatGPT and Gemini, and there seem to be a few nice open source or freely available tools for handling 3D images.