Hardest game ever made, Little to no story, All action and A whole lot of monsters packed into one room.
This game has good replay value from my perspective, i enjoy coming on for a round just to blow 20 minutes... The Plutonia Experiment is the standout of the two 32 level episodes.
The final level in The Plutonia Experiment pits you against all monsters having their last go at you, you get rounds of all of the monsters (sorry i forget their names). Not to mention something like 8 of the huge mothers :p.
Just running through this game on god mode should show you how freaking hard this is for any level gamer. I have never come across such a hard game.
This game still has the puzzle elements, which can leave you running all over the map trying to find the next key, but hey thats one of doom's reasons why it succeeds.
Gamespot got this one wrong. I'm sorry but it seems they looked at this game from a noob with no FPS experience's perspective