Prince of Persia 1

Start the game with PRINCE MEGAHIT. 
(In version 1.3 use IMPROVED). 
This will give you access to the following cheat keys.

 [U]          - View screen above
 [H]          - View screen to the left
 [J]          - View screen to the right
 [N]          - View screen below
 [Shift]+[I]  - Inverts the screen
 [Shift]+[B]  - Blanks out non-animated objects
 [Shift]+[W]  - Float down
 [Shift]+[S]  - Heal a health point
 [Shift]+[T]  - Add a health point
 [Shift]+[L]  - Advance to the next level
 [+]          - Increase time
 [-]          - Decrease time
 [K]          - Kill the guard you are fighting