ID Software has been a part of gaming since a sprinkling through the 80's but they came in hard straight through the 90's and beyond. John Romero began working at Softdisk, met Adrian Carmack, John Carmack (no relation) and Tom Hall. They put together a crack team of developers of various origins and talents and some how that all added up to give us Wolfenstein 3D, Doom, Quake and so many other games that still stock shelves to this day.
Wolfenstein 3D kicked off their reputation and brought about violence and killing to the Third Reich with a chaingun. The world had never seen anything like it and there was a new first person perspective with a gun in the middle. Like, some sort of shooter that you can see from the perspective of the first person. I'm sure that name will catch on. Wolfenstein was blocky, choppy and had its quirks with level design and challenge, but it started something that only exploded with the next coming.
Doom and Wolfenstein brought about a whole new line of games on top of their own offshoots of Doom 2 and Wolfenstein: Spear of Destiny. Those were the only real sequels they created for them personally. Doom 3 was less than half the original team and Wolfenstein's further sequels were handled by different developers such as Raven and Gray Matter Studios.
Quake, on the other hand, was the final game created by both John Romero and John Carmack. This game did not turn out the way that they wanted, but that really didn't matter at all. In fact, the way they wanted it before was with fantasy hammers and swords with melee combat being the primary function. What we got was Doom on 3D steroids with evil ogres and monstrous creatures with gothic structures. It was gorgeous.
The amazing 3D world of Quake started an amazing revolution of amazing games that still function to this day. Quake 2 was not as well received, but it was definitely no slouch with gameplay and graphics while still remaining a Death Match favorite. Quake 3 Arena cut through the fat and became one of the top arena fighters in a market that now had a thriving demographic that was hungry for more guns and more blood. Now, you can partially customize your own Doomguy and play as him, Bitterman from Quake 2 and Ranger from Quake. It brought about whole new characters and designs for what is known as the "Doom-verse".
Doom is going to be a very large theme on Planet Virtua! That is just something that you're going to need to get ready for.