There is no entropy generation here, it is based on the Mersenne Twister, so it is pseudo-random only at this point. If none is provided, the seed is just the current timestamp.
This is good for repeatability, bad if "true random" is needed.
Problem is, this is very tricky. I'd like to add it at some point, but finding a way to add entropy that works both in the browser and in Node would be quite difficult. For example, I could use mouse/keyboard in browser, but not in some server app running on node.
I could use an external service (like random.org) as the underlying random (I built it in such a way that this was easily swappable/replaceable), but then I'm adding network latency. I show an example like this in the docs: http://chancejs.com/#browser
So for now I'm punting on it, with a plan to revisit later.
