Rainbow Six: Vegas 2 Codes -

Unlock MTAR-21
At the title screen hold and press the following buttons to unlock MTAR-21 Assault Rifle: x2, x2, , , , , , x2, .

Unlock M468 assault rifle
Hold and press , , , , , , , , , , , at the title screen.

Unlock Third person view
Press to pause game play during an offline single player game, then hold and press , , , , , , , , , , , .

Unlock One hit-kills
Press to pause game play during an offline single player game, then hold and press , , , , , , , , , , .

ACE and XP Farming
Found a spot to gain ACE and XP easily? Simply perform the actions you want for ACE and XP, then before you hit the next checkpoint, let one of those wannabe terrorists kill Bishop or Knight, forcing you to reload the checkpoint. You keep the ACE and XP you acquired (just don't turn off your system) and you can re-do that section again for more points.

Getting ACE Points With Teamwork
Your computer allies are great for taking out enemies for XP, but not for acquiring ACE points. Keep them back if you can handle a firefight by yourself, since enemies killed by your team will not add ACE points. Players who are using Bishop and Knight will gain ACE points respectively in co-operative Story mode. Just remember to keep the CPU team away. This does not apply for Terrorist Hunt and adversarial Multiplayer.

ACE Point Actions
You can view the required actions for ACE points when you pause the game. They are:

Assault ACE Points
+3 Kill an enemy or player behind cover with penetrating weapons.
+3 Kill an enemy or player with C4 (it must be C4)
+2 Kill an enemy or player who is using a mounted machinegun
+2 Kill an enemy or player with a frag grenade or breaching charge (i.e., something that's not C4)
+2 Kill an enemy or player who is using a riot shield

Marksmanship ACE Points
+3 Kill an enemy or player at long range (about the size of your targeting circle at its widest diameter)
+3 Kill an enemy or player when they are on a rope (fast rope or rappelling)
+2 Kill an enemy or player while you are rappelling
+2 Kill an enemy or player who is sprinting
+1 Kill an enemy or player with a headshot (any weapon, although a long distance headshot will result in a long distance kill instead)

Close Combat ACE Points
+3 Kill an enemy or player at short range (their height should be a third to half of the size of your screen on either standard or hi-def)
+3 Kill an enemy or player who is stunned or flashbanged (vision impaired)
+3 Kill an enemy or player by blind-fire (this range may be slightly more than the short range kill distance)
+3 Kill an enemy or player from behind (distance may change this to a long range kill)