The open source portfolio really is kind of a golden standard. It is real work that you have done, that has (hopefully) advanced the commons, because you love programming and have something unique to add to the world. Some fake video game programming may indicate something, but is simply not as strong an indicator.
Who are you going to hire- TJ Holowaychuk, who wrote Express, or the guy who placed 3rd on TopCoder in 2012?