It wasn't just the engineering. The immersion was unprecedented in videogames, which was supported, besides the obvious rendering improvements, by lighting and

It wasn't just the engineering. The immersion was unprecedented in videogames, which was supported, besides the obvious rendering improvements, by lighting and sound. Experiencing for example, lights suddenly turning off and monsters appearing and making noises behind the player, was very intense and novel. (There were also other revolutionary aspects in Doom, notably, multiplayer)