A Very Brief Description 

of Enemies and Objects in Wolfenstein

Guard: These guys wear brown. They're slow, but there's lots of them! You can kill them easily.
S.S.: Blue dudes with bullet-proof vests. Hard to kill. At least you get a machine gun when you kill them.
Officer: White guys that are hyperactive and lightning-quick with the gun.  Don't ever get caught using a pistol in front of one of these!
Mutant: Green, undead guy who's about as bad as an officer except that they don't say anything. They shoot TWO times.
Dog: HA! These suckers are easy to kill!
Big Biff: Big, fat, blue guy who have huge chainguns. Shoots 6 times. Comes with gold key.
Spike: Same as Big Biff, but stronger.
Ubermutant: Same as Spike, but even stronger.
Dr. Schabbs: He looks like a baker gone bad. Throws syringes at you that are like rockets. Comes with gold key.
Deathknight: I don't even want to tell you about this guy! Comes with silver key.
Hitler: He comes in two flavors: Armed and un-armed. If you kill him in a level EVEN if it's not the last level, you win the game.
Ghost: Ick! You can't kill THESE things! These are rumored to only be seen in the Castle of Lost Souls.
Pistol, Knife: You start out with these. Yipe!
Machine Gun: Good but not good enough.
Chain Gun: Get this as quickly as possible!
Flame Thrower: Useful in the right spot.
Missle Launcher: Use this to kill bands of Nazis or big bosses.
BFG 9000: Hey! Wrong game!
Treasures: Things that have yellow on them are treasures. Get 50 of 'em to get a new life.
Ammo: Clips and ammo boxes are for pistol, machine and chain gun. Gas is for flame thrower. Rockets are for missle launcher. Backpacks let you carry more ammo.
New Life: You gotta be lucky to find one of these...most of the time.
Lights, Puddles, Tables, etc: Either used as decorations or secret door indicators.
Gold key and silver key: Used to open doors of the same colors.
Secret Doors: These lead you to either trouble, fortune, or items to make you able to advance to the next level.