Doom is great simple fun that was just unbelievable at the time. The keyhunts can be annoying your first time through, but as you play through the game more and more and familiarize yourself with the level layouts, you'll find the game more and more fun. The heavy metal aesthetic, reflected in both the music and the awesome and iconic monster designs, is hard not to love unless you hate fun. The gameplay structure of making your way through levels and blasting away all the monsters in sight with your whole awesome arsenal is primally addictive. And that's before you factor in deathmatches and insane modability, though the latter technically moreso comes in with Doom II. Doom is the shit.

Just remember, there's no shame in playing it with GZDoom and mouselook.