Insane mode
     Successfully   complete  the  game  on  the  Casual  or  Hardcore
difficulty setting to unlock Insane difficulty setting.

Secret gamer picture
     Successfully  complete  the game on the Insane difficulty setting
to  unlock a secret gamer picture. It has the Red Gear's Symbol behind
Marcus.

Faster reload times
     When  you  press  RB  to reload, there will be a clear bar with a
small  white  segment  somewhere  along  it. It will appear where your
bullets  used  to  be.  There  will also be a smaller white bar moving
across  the clear bar. As soon as the white bare gets inside the white
segment, press RB again. This will reload your weapon much faster, and
if  timed  just  perfectly,  will give your gun an extra boost in fire
power.  However,  if  you do not time it correctly, the clear bar will
become  red and it will take even longer to reload than if you had not
attempted it.

Emergency holes
     When  an  emergence  hole  opens up, toss a grenade into it. This
will automatically close the hole, and therefore keep the locusts from
coming out.

Finding C.O.G. tags
     In Campaign mode, look for the dead soldier symbol (red gear with
skull  inside)  painted  on  a  wall,  floor,  or other location. This
indicates  that the Locust have killed some Gear soldiers in the area.
Because Gear soldiers wear C.O.G. tags, you should be able to find one
nearby.

C.O.G. tag location in Act 2
     When  you  reach  the  part  with the spotlight, instead of going
straight, go to the left. You should find a C.O.G. tag there.

Defeating Berserker
     In  the  final  level,  you  first  need  to  get the Berserker's
attention;  Berserkers  are  blind.  They only go off smell and sound.
Lead  her  all  the way back to the very first train car. While she is
still  on it, quickly run off and press the button to release the car.
The train car will collapse and the Berserker will go with it.

Defeating Boomers
     Boomers  have rocket launchers that can usually kill you with one
hit.  In  order  to  kill  them safely, take cover and wait until they
shoot  at  you  before  you  start  shooting  back. Just as they start
reloading is the best time to shoot them, because their gun has a very
slow  reload.  After they reload, hide again and let them fire. Repeat
this a few times to kill them.