Half-Life 2 would be the one to truly define the series thanks to an exquisite physics model and interactive story like no other, but all that execution on a given formula wouldn't of come about if Valve's first iteration hadn't existed. Putting you in the shoes of one Gordon Freeman and arming you with a now-iconic crowbar, it's not until you go back and journey through the Black Mesa Research Facility (and beyond) that you'll truly breathe in just how influential this unassuming masterpiece really was. 'Cutscenes' that let you control the camera as actions play out? That was Half-Life. Hybridising gameplay and puzzle solving, the former of which being entirely physics-based, its large set-piece battles can still be seen as influencers to this day. These are just two indicators of Valve's contribution to the industry, and considering we almost didn't get it at all when development assets went south and the whole thing had to be rebuilt, it's yet another case of a video game success story everyone should pay tribute to when they get the chance.
