This robot differs from other spring-mass-based bipeds in the type of actuators used -- specifically, quasi-direct-drive rather than series-elastic. This allows the "springs" to be implemented in software rather than hardware, simplifying the design and reducing cost.
This is the actuator I designed for use in this project: OpenTorque Actuator
The project will be split up into 2 stages. First, I'll build a simplified, 2d planar biped capable of walking on a treadmill. Once that works, I'll add the other 6 actuators (yaw, roll, and ankle pitch for each leg) for a complete, fully-functional robot.