More details can be found in the original contest posting, but to register, it basically comes down to doing the following steps:
1. Follow @Phoronix on Twitter; the official Phoronix account where new articles and news items appear.
2. Follow @MichaelLarabel on Twitter; the feed where information about upcoming Phoronix stories, Linux notes, beer thoughts, Q&A with readers, and more is offered.
3. After following both accounts, then re-tweet: "@phoronix @michaellarabel are giving away the #Unigine #OilRush game http://goo.gl/BRJUs" (or anything to that effect; you're welcome to get more creative).
This contest is going through the 6th of June.