Despite its minor upgrades, Doom II: Hell on Earth is an awesome game that never ceases to get old
The title introduces some new features, such as a double-barrelled shotgun, new monsters to fight and more unique level designs. The sounds are all the same, with the great simplicity to follow it. That's what makes the Doom games so great, in my opinion, is their simplicity.
I also enjoyed the references to id's other titles, like Wolfenstein 3D and others, as they made their way into Doom II as well... mostly in the final levels in the game. This is a must play for anyone interested in the good old shoot-em-up style games, or any shooters for that matter. This is a title that one should pick up and play.