Offers a totally different gaming experience, but it's equally entertaining as the real thing, I'd say I played this as much as Half-Life. And I managed to bring a hat with me to the borderworld (or Xen). Crowbar Collective expanded on the gameplay experience by adding their own ideas which they've implemented very well, but also at the cost of other stuff, deprecated levels, but also a total expansion and new ways of play which truly show that they went as far as they could in fully using the engine.