Superman: Shadow of Apokolips Cheats

Play as Clark Kent
Enter "Secret Identity" at the cheats screen.

Play in slow motion
Enter "Slow Motion" at the cheats screen (unsure what this does at this time, even though it seems obvious)

Free Range Mode
Enter "Wanderer" at the cheats screen.

Unlock Everything
Enter "I Want It All" at the cheats screen.

Extra Hard Difficulty
Enter "Nails" at the cheats screen.

Secret Icon Locations
a day in the life - the right side of the police station, smash the ZZZ wall (thx Xeno)
officer down - inside one of the smashed wall rooms above you when you enter
flood damage - on top of the dam in the right hand unit
infiltration - on the right hand side of the bomb room behind a pillar
incursion - after you beat the room full of bots, go back where you started to a door that is now open
liberation - smash the top of the dome steel factory showdown - in a corner with a bunch of crates that has a small opening on top in the middle mountain
strike - the room where you have to deactivate lasers, there is a stream of lava and a grate that you can break apart
reactor meltdown - under the bridge that kanto stands on
uprising - the first courtyard you protect the guards in, you can break away one of the doors that leads to it
guilty as charged - there is a door in the center, at the end of the hallway
duel in metropolis - fly up, follow the elevated street
unfinished business - the room before luthor's office, behind some furniture
face off - in a upper corner behind some crates