Until recently, all the map tiles were created in Photoshop (or Pixelmator, or Affinity Photo, let’s not get into that now) and exported as flat images. Multiple combinations of ground × road × water × dirt all had to be done up front and each new one took additional memory and disk space.
I created a new meta tile system that improves this. Each tile now consists of multiple layers which are combined at runtime.
The first “naive” implementation simply draws all the layers on top of each other, which isn’t super efficient but I have an improved version in the works which uses multiple texturing units and a shader which combines them in a single pass.
Using the new tile editor I can create any combination of water / ground / road layers I need and the game and level editor will start using it immediately.