This looks great, but how do I plant a seed? Also, how did you add a background outside of the window's viewport? I'd really like to know.
The game window is a Viewport node, with the game itself added as a child of the viewport. The viewport is set to render at 64x64 pixels and I use a script to draw it as big as possible in the window. The background is just a checkerboard pattern added behind the rendered viewport.