Even for a modern gamer, this game is highly addictive and fun.
I first played Doom January 2009, when a friend brought it to school to put it on the computers in our computer class. I agreed to try to install it since most school computers wouldn't let us install anything.
So I installed it, and I was amazed at how good Doom is after 15 years.
When I first played it, I was a bit scared, not knowing where anything is, but I learned fast.
The graphics, though dated, are still good, and it is really fun to navigate the dark halls, waiting to fire at any demon that dared entered my line of sight.
All of the weapons are useful, though some, mostly the fist (unless you have the berserk pack) and the pistol, are near useless against stronger enemies, such as the Barons of Hell. The ultimate weapon is the BFG 9000, which can kill everything in 1 to 2 shots.
The variety of demons are immense, varying for the zombies, to the imps, to the Cyberdemon, and some you really do not want to encounter without a rocket launcher or a plasma rifle.
The multiplayer is still fun, and Doom was the first game to feature Deathmatch, which is my favorite competitive mode.
One great thing about Doom was its ability to be modified. It still has people making new levels, enemies, and weapons to this day.
Even though Doom is 15 years old, it is still as addictive as ever and remains one of the best FPSs ever.
I give Doom/The Ultimate Doom:
97%
A
On a side note, you may want to use a source port, such as Skulltag or Doomsday, to enhance the game. Most include the ablility to jump and to use free look. Some even include new weapons and demons.