I'm in the process of putting together a City Building game for the Challenge. The game's required social aspect is that you are being watched by a ‘virtual’ audience and they will make requests which you can complete to earn Goal Credits. These allow you to build bigger and better buildings.

The game is viewed from an isometric perspective and it is my first isometric game. I drew the tiles as usual from top left to top right then the next row down left to right but then I realised this doesn't work. The map needs to be in a diamond shape and projected onto the screen so 0,0 is the top of the diamond then the next row down is 2 tiles 1,0 and 1,1 then the next is 3 tiles etc.

I found some maths online which allows me to draw and project the tiles and also to calculate the other way around eg which tile my mouse is hovering over.

Other than that it was pretty straight forward to program, I added a nice bloom shader I found (is it too much?) tidied up the GUI and downloaded some free music to play.