By default, Infinite only has three available difficulty settings: Easy, medium and hard, with the 1999 Mode – which tunes Irrational's latest game to a difficulty best suited for those looking for a classic shooter experience akin to System Shock 2's campaign – hidden away until the game is complete. If players decide they want an immediate challenge, using the Konami code will allow them to unlock it at any point.
- On PC (with keyboardmouse): Up, Up, Down, Down, Left, Right, Left, Right, (Cancel key), (Confirm key)
- On Xbox: Up, Up, Down, Down, Left, Right, Left, Right, B, A
- On PS3: Up, Up, Down, Down, Left, Right, Left, Right, O, X