It might be surprising, given that the last decade saw World War 2 shooters become as prolific as hormonally unstable diatribes on Justin Bieber's @reply tab, but the setting really hadn't been explored by games very much before Wolfenstein 3D. There were a few flight and vehicle command simulators like The Red Baron, Silent Service, and Conqueror--but little in the way of pure action games. Perhaps due to understandable reverence, gaming's treatment of WW2 was sparse and largely limited to more cerebral, slightly distanced experiences. The visceral, harrowing, on-the-ground action just wasn't represented. Obviously, Wolfenstein 3D blew the doors off that in 1992.
Now of course Wolfie is no poignant, historical document. It doesn't pretend to be for a second. But by giving World War 2 such a balls-out, explosive, cartoony treatment, it definitely opened up a whole new avenue for the conflict's exploration in gaming. As ancestors go, it might be Medal of Honor’s slightly embarrassing, socially inappropriate Grandad. However, without its selfless historical efforts, we’d all be speaking German now. Or something. I’ve lost the run of this metaphor, to be honest.