Gain most of the points you need to upgrade a skill. Pass a checkpoint with enemies positioned just after it. Defeat those enemies to gain the experience required for the desired upgrade. Make the upgrade and then then die before passing through another checkpoint. Now you will return to the last checkpoint, with your points restored but with the upgrade you selected already in place. You can repeat this process to gain additional upgrades until you are ready to proceed as normal.
King Sword
Beat The Beast a third time to get the magical sphere powers. Return to the second stage entrance for the Crystal.
Prince of Persia Classic
At the start of the game, go to the first waterfall for the Green Retro Potion.
Prince Sword
At the entrance to the tank, step on the bug to unlock Squish.
Sand Dagger
On The Challenge of Wisdom, go down the stairs and get ontot he pipe to get Cannonball.
Screen saver
If you wait long enough without manipulating the controller, the camera will begin to display different close-up angles of the prince. Also, depending on the area, it will show a cinematic tour of your current location.
The Sands of Time Prince Costume
The Menagerie of the Myths holds the Blue Retro Potion.
The Two Thrones Dark Prince Costume
Search The Water Bearer's map for the Red Retro Potion.
This is Persia Achievement
This task involves kicking an enemy into the pit. The ideal enemy for this is the priestess, who normally dodges all of your attacks. To trick her, stand so that the Prince is next to a pit, with the edge to his side and the priestess in front of him. Chain together four attacks so the Prince should end up facing away from the pit with the priestess behind him. If not, move away and try again. If she is, quickly freeze her in place and attack once more. It should be a kick that sends her off the edge.