Doom II: Hell on Earth is a first-person shooter video game created by id Software. It was originally released on the IBM PC on October 10, 1994. It is the sequel to Doom, which was released a year earlier. In 1995, Doom II won the Origins Award for Best Fantasy or Science Fiction Computer Game of 1994. Unlike Doom which was initially only available through shareware and mail order, Doom II was a commercial release sold in stores. Master Levels for Doom II, an expansion pack that includes twenty one new levels, was released on December 26, 1995 by id Software.
The player progresses through 30 levels (32 including two secretly accessed levels), and on the way he learns that the remaining survivors of Earth's population are being held on Earth and the only means of escape is the space port with massive ships that can carry the remains of Earth's population into space. However the demons know this and have placed a fire force field over the space port, so those ships cannot land or leave. The marine must battle his way through the infested space port and deactivate that fire force field. Once humanity is finally evacuated from the ravaged, infested planet, the Marine is the only human left on Earth. He sits and waits for death, content in the knowledge that he has saved his species, giving them a chance to continue on elsewhere. Only minutes pass before the Marine receives an off-planet transmission - humans in orbit have managed to find out where the armies of Hell are spilling from. If the Marine can reach this gateway, he can thwart the invasion once and for all.
The Marine wearily pulls himself to his feet and moves off to the portal, cutting a swathe through the demons in his path before finally arriving at the gateway. He sees no way to close it on this side, and so dives through to find a solution on the other side. In the game's own words, "what do you care if you have to go through Hell to get to it?"
After brutal battles with legions of Hell, the Marine finally reaches the home of the "largest demon (he has) ever seen." Once the player fires enough rockets into the exposed brain of the demon, dodging constant attacks from lesser demons the larger one summons, the demon (known as the 'Icon of Sin') explodes, devastating Hell in its death throes. When the chaos finally ceases, Hell is in ruins, the invasion permanently halted. The Marine wipes his brow and begins the long journey home, looking forward to helping to rebuild Earth.
The main additions to the game were the additional monsters available for the player to fight. Doom II doubled the amount of non-boss monsters and started using bosses from the original Doom as normal level enemies. In addition, the multiplayer functionality was greatly improved in Doom II, including "out of the box" support for a vastly increased number of dial-up modems. The two player dial up connection allowed one player to dial in to the other player's computer in order to play either co-operatively or in deathmatch style combat. There was also LAN functionality added, which was improved upon as patches and updates were released.
The only new weapon addition was the double-barreled shotgun, which could fire out 20 pellets instead of the regular shotgun's seven, making it very useful in dispatching Demons, Cacodemons, and any form of medium-sized monster.
There was also one new item created: the Megasphere, a tan sphere that could give the player 200% armor and health.
A small change in gameplay was instituted. Instead of the player playing through three related episodes, gameplay takes place over one giant episode, albeit there are interludes for when the story develops. Instead of watching the player's progress on a map (as in the original episodes of Doom), the screens between each level simply show a background. It also meant that the player would not have to start over with a pistol every eight or nine levels (as was the case in Doom, since each episode consisted of nine levels, including bonus levels).