After my success with Doom 2, I decided to give Doom a try, since I never actually finished it. When I was a kid, I started with Doom 2.
It is definitely slower paced. But also it’s secrets structure is crazy. Consider the 3rd level of the 1st episode, Toxin Refinery. You find the yellow key, but you don’t need it to exit the level. Instead, the yellow door is behind a secret.
One element that I like more in Doom is how they show you progress on a map:
The first episode is rather boring. There are just a few weapons: shotgun, chaingun, rocket launcher. And only a few enemies. Two barons of hell are the final boss.
Also the design of the last map is fun, with this huge pentagram:
