I fell in love with playing Minecraft with my kids. I loved the spatial metaphor of defining each bit of air around you with a block, and allowing the player to redefine that space on the fly. I thought long and hard about how to incorporate this idea into a math game. Unfortunately the web is not ready yet to deliver a high quality real time 3d experience to players through web browser.
I started to play with isometric blocks. These are blocks that look like they are in perspective (receding in space) but in fact they are all the same. They can give the illusion of space but can be managed much more easily than real 3D.
After some experimenting I came up with the idea of displaying a three by three block like a Rubik’s Cube. I added to that the ability to remove and add blocks. The blocks have symbols on them, so the player needs to choose the blocks in a pattern to make a math equation that is true, in order to permanently remove the blocks. There are 4 types of gems to discover as the player moves down into and across the blocks.
Admittedly its a bit of a stretch from the original inspiration, but I think it can work for some kids and it also allows for creativity in making equations that evaluate to true.