I played Doom for the first time in 2015 at the age of 22 and found it pretty damn scary. Things like the first two boss fights carry unmistakable traces of horror design. It's weird that people treat horror and action in Doom like some kind of either/other as they compliment each other quite nicely, I haven't played Doom 3 or finished Doom 4 but perhaps it's partially their fault for focusing mostly on one aspect over the other. Being scared or getting tensed playing Doom has nothing to do with being a kid, it's about being inexperienced at the game. You may now know with experience that a baron can easily be circle strafed with a shotgun but for inexperienced players the heavy damage you can take from that, not to mention the lack of experience at circle strafing and the tension from fighting off whatever trap it is that Sandy Peterson threw you in, can be pretty overwhelming. I think Doom 1 (and 2 for that matter) is unmistakably a horror game, having sense beat both twice on my recent UV play through I was still getting tense on a level like Monster Condo with the flashing lights and sudden nasty traps. It is also unmistakably an action game with PAR time that encourages you to rip and tear through everything but, with the exception of it's lowest-tier enemies, this is only something that can be done with experience and dedication to the game. Doom 1 doesn't "age" it's players simply mature. The interplay between the two aspects of the game is timeless design and why it still blows away other FPS games. That or I really suck.