Half world has a massively extensive (large) amount of script, so if it gets a little bit laggy, that's expected. It still needs heaps more backgrounds, and is not finished. As the tittle suggests, it is still a WIP. Keys: Traditional W,A,S,D, Space to speed/sprint, there are other keys that enable extra life, but you will only find these if you dig through the massive script :-).
theSpazticOctopus Helped me with the initial coding, and he has many of his own sophisticated games.