To open up a level select option, insert the following password on the title screen: Up, Down, Left, Right, Up, Down, Left, Right.
For unlimited ammunition, insert the following password on the title screen: Up, Up, Down, Down, Left, Right, Left, Right.
Obviously, weapons in Manhunt 2 exist for a huge primary reason -- to kill your foes brutally. But a lot of items also have alternate uses. For instance, weapons like the machete, meat cleaver, knife and glass shard can cut various ropes you encounter throughout the game. The knife will allow you to pick locks, the crowbar can break open padlocks, and a well-placed bullet from your firearm can eliminate locked door handles.
To unlock a bonus level where you play not as Daniel, but as Leo, you must complete the game once through. Thereafter, this mission will become playable.
Successfully complete the game, which will unlock the "Relive Scene" option. This will allow you to go back and play any mission over again.