No it wasn't your stuff that was the problem. Couldn't create an account with the stupid site! Isn't STEAM just a general gaming platform, or was your thing specifically called that?
3 Dimensional Cubic Chess 8x8x8 Board

I didn't create steam - its made by valve the company that made Half-life the game. It is the main platform for PC gaming online. Thats why i figured it would be a good place to put the game for people to be able to have a look but in your case it just doesn't seem to want to play.
It is in general not too bad and has a good reputation for customer support. Which I can attest to - they are quick and effective at solving bugs. This could be one that is slipping under their radar.
Its far from a finished product.
One idea that I have been toying with was loading stockfish ( for fairy pieces ) - it can handle 3d as far as I am aware. The issue was that it's license was open sourced and anything that runs it has to be open source. The choice was between having a homebrew AI or no AI.
But in theory - I could allow for any engine to be loaded as a submodule and it would not be part of the game - the open source license would not apply anymore - then you could have a choice between ; bad AI , no AI ( if you choose not to load the submodule ) and good AI.
Anyway - stop ripping on the bad AI - that was like 3 weeks worth of work VS 9 months for everything else and its not finished yet. I genuinely considered just coding it to just make random moves as no body ever wants to play bots anyway. I think it does alright considering ; it has to work with lots pieces , in different modes ( mana , modded , 4 player ) and under different movement rules - eg. 3 moves per turn.