Growing tumours in silico can be very entertaining, much more than growing them in your body. I have written this program (Windows only) which has a simple user interface enabling you to set the parameters of the simulation and run the code while displaying the growing tumour in a window. This is how it looks like:
When you press “OK” and wait patiently a few minutes watching the growing ball of cells, you will see something like that:
A full version of the code (Windows/Linux/Mac) used in simulations from the Nature paper which however does not have the graphics user interface is available here.