This process was a 3-step process: Phone Screen, In-Person Interview, Puzzle Challenge Interview. Each step was pushed along very quickly compared to other companies I interviewed for in the area. Just to give you an idea, I only got a call from a different company in Philly a month after applying, but Quintiq called me back for a phone interview within the same week I applied. They move fast and its a good thing, some companies seem to waste potential employees time, adding stress in an already stressful process.
The phone screen is used to learn about your skillset and what knowledge you have. The in-person interview is to understand who you are as a person, whereas the Puzzle Challenge is to see you apply the skills mentioned in the phone screen in a fun puzzle exercise.