HL2 was a bit of a joke. You're still boxed & for all the physics you have absolutely no freedom. Consider the driving portions, you're always in a passage, veering from it results in death (Dune buggy section) or a vertical face which can't be climbed. All HL2 was put a sky texture up instead of a ceiling. 1 of the only games which gives you an true freedom to complete a level as you wish was Operation Flashpoint.