Doom, Duke Nukem 3D, and Dark Forces are my triumvirate of that era. Of all of them, Duke Nukem felt the most interactive. There are times I would clear a level of enemies, then play with all the gizmos the level designers put inside like the jail cell block doors of Death Row. The security cameras were so advanced at the time too! They rendered their view, in real time, on a wall TV. I wouldn't see that effect again until the 2000s. The levels felt intuitive too, at least the Earth levels, that I felt like an urban explorer in a way that Deus Ex would later capture.