Bat-man
Clear Chapter 2 using Nigel the Bat |
A surprisingly challenging achievement, depending on your skills and willingness to cheat - the bat mask (AKA Nigel) reverses your controls. W will move you down, D will move you left, and so on. The mask is unlocked when you witness the secret ending after finding all of the puzzle pieces and putting them together.
If you're playing on PC, the challenge can be entirely sidestepped by just remapping your controls. On the main menu, visit 'options' and 'controls', then hit the enter key. You'll then need to input a new key for each direction; to perfectly reverse them, type S,D,W,A.
If you're playing with a controller, holding it upside down might help, but your only real option is to rely on guns and locking on to your enemies - melee is a real pain when you move around like a drunkard.