Speaking of changing everything, Valve's second major Half Life title gave us a gamer's paradise of physics-based mayhem, coming out at a time when our curiosity urges were in need of scratching with new technology, all the while providing one of the best first-person narrative campaigns in gaming history. Playing once again as the forever-muted Gordon Freeman, the one thing nearly every gamer mentions when reminiscing over HL2 is the Zero Point Energy Field Manipulator (or Gravity Gun for short), a fantastic little device that upon its unveiling in 2003 prompted every game developer under the sun to utter "Why the hell didn't I think of that?!". Relatively simple-sounding, yet oh-so-fun in execution, this allowed you to grab many parts of the environment and fling them at your foes, as well as charging up a more standard force-blast attack that would send enemies and debris flying along with it. Thanks to a suitably gorgeous graphics engine and combat that is just still so incredibly tactile and immensely satisfying today, there's good reason every gamer worth their salt is clamouring for anyinformation on the next instalment.
