I loved Portal and still do. It is one of those games that is just my style. The physics system is amazing at it is such a challenge trying to figure out how to beat a course with the least amount of portals, then again in the least time, then again with the least steps. Each time through I have to sit and stare at the screen for a bit just planning things out and getting frustrated... but it is always very fun. (I still can't beat all of the Least Step challenges though ><)