Doom is a series of twitchy, fast-paced first-person shooters with mild horror elements, developed by id Software and published by Bethesda Softworks. They have a stronger focus on their single-player campaign than most recent first-person shooters, though most games in the series do have a multiplayer component (and some multiplayer trophies) as well.
Trophy-wise, the new games have moderate-to-low difficulty and can be platinumed in 25 hours or so, while the older games are significantly more challenging (due to the player having to beat the game on the hardest difficulty setting, for example).