Mass

Mass in Doom is a little different than the scientific definition of mass. Doom has a very basic physics engine. Every object is assigned a mass value. And every projectile has a certain amount of force value that pushes an object in the direction the projectile was originally going, Assuming the object has a shootable value, such as a monster or barrel. Objects that are decorations such as dead bodies or items don't need mass values as they are not actually moved by anything. When a projectile such as a plasma gun bolt makes contact with an object, the contact will move the object slightly. The math is simple. The higher the mass is, the less the object will move when made in contact with a projectile. The lesser the mass, the more the object will move. The player's mass also defines how much he slides when he attempts to stop running.