. "The game involves a lone Marine investigating a distress call from one of Mars' moons, which the player (controlling the Marine) must make their way through over a dozen levels, trying to stay alive while battling against a variety of creatures, ex-Marines, and various other dangers, such as traps that can cause damage, if not death to the player. There is also a multitude of weapons for the player to pick up and use, along with ammo and several ways to increase a player's health and armor status. There are also various secret rooms and a variety of functions needed for the player to utilize in order to open up more areas of levels (i. e. such as using keys, pressing buttons and flipping switches found in areas of the game) in order to make it to the exit. The player only has one life, although they can save the game at any time, along with having five skill levels to choose from. As far as the sequel of Doom 2 went, all the graphics, controls, and weapons were the same as the original, with only a couple of additions, such as the Super Shotgun being added and a Mega Sphere to increase a player's health and armor to 200%. However, the gameplay was widened by adding the ability to jump (actually the player couldn't physically jump, but there were many levels where the player had to jump, or fall down a distance in order to make it through various levels) and by having several additional monsters added to the mix."@en . . . "The Depths of Doom Trilogy"@en . "The game involves a lone Marine investigating a distress call from one of Mars' moons, which the player (controlling the Marine) must make their way through over a dozen levels, trying to stay alive while battling against a variety of creatures, ex-Marines, and various other dangers, such as traps that can cause damage, if not death to the player. There is also a multitude of weapons for the player to pick up and use, along with ammo and several ways to increase a player's health and armor status."@en . . .