Hoarder is an unlockable achievement in the exclusive Xbox 360 port for the classic Doom game. It is unlocked when collecting all items in one of any level.
Strategy[]
There is an easiest way to unlock this achievement in few levels. In Episode 3's E3M1: Hell Keep level for example, there are 6 Health Bonuses and 2 Armor Bonuses to find.
Note that the achievement cannot be unlocked in multiplayer mode.