Call Of Duty : Modern Warfare 2
One Man Army is a Tier 1 perk in Call of Duty: Modern Warfare 2 which allows the player to switch classes without needing to respawn (there is a 5 second waiting period when you switch). Even though One Man Army is a Tier 1 perk, it also replaces the player's secondary weapon with a backpack (its still in the secondary weapon slot). When the player switches from their primary weapon to the backpack, it brings up the class menu. From there they can pick the class that they want to switch to. It is unlocked at Level 45.