The main objective of the player is to lead the unnamed protagonist out of dungeons and into a tower before time runs out. This cannot be done without bypassing traps and fighting hostile swordsmen. The game consists of twelve levels (though some console versions have more). However, a game session may be saved and resumed at a later time only after level 2.

The player has a health indicator that consists of a series of small red triangles. The player starts with three. Each time the protagonist is damaged (cut by sword, fallen from two floors of heights or hit by a falling rock), the player loses one of these indicators. There are small jars containing potions of several colours and sizes. The red potions scattered throughout the game restore one health indicator. The blue potions are poisonous, and they take one life indicator as damage. There are also large jars of red potion that increase the maximum number of health indicators by one, and large jars of green potion that grants a temporarily ability to hover. If the player's health is reduced to zero, the protagonist dies. Subsequently, the game is restarted from the beginning of the stage in which the protagonist died but the timer will not reset to that point, effectively constituting a time penalty. There is no counter for the number of lives; but if time runs out, the princess will be gone and the game will be over, subject to variations per console versions:

1. The DOS version allows the player already in the very late part of Level 12 to continue after time is out with no extra life, so:
   • Restarting the level by pressing appropriate buttons is not death, thus not failing the game yet.
   • ny player's death, including having killed Jaffar then falling from excessive floors of heights, also fails the game in which case the Princess is also gone.
   • Only defeating Jaffar and exiting Level 12 alive will still save the Princess, with a negative time score in the hall of fame.
2. The Macintosh port will not give the player a game over once they reach the final area of Level 12 (stored in data as Level 13), provided they make it there on time. The player must cross the magic bridge and make a screen-transition to a room with falling tiles to be 'safe'; once there, they will always be allowed to continue, regardless of deaths or time expiration. Running out of time at any point before the screen-transition, including the bridge, will result in game over as usual.
3. The Super NES remake allows the players to save themselves after time is out, to get the game over at the end without the princess saved.

There are three types of traps that the player must bypass: Spike traps, deep pits (three or more levels deep) and guillotines. Getting caught or falling into each results in the instant death of the protagonist. In addition, there are gates that can be raised for a short period of time by having the protagonist stand on the activation trigger. The player must pass through the gates while they are still open, avoiding locking triggers. Sometimes, there are various traps between an unlock trigger and a gate.

Hostile swordsmen (Jaffar and his guards) are yet another obstacle. The player obtains a sword in the first stage, which they can use to fight these adversaries. The protagonist's sword maneuvers are as follows: advance, back off, slash, parry, or a combined parry-then-slash attack. Enemy swordsmen also have a health indicator similar to that of the protagonist. Killing them involves slashing them until their health indicator is depleted or by pushing them into traps while fighting.

In stage three a skeletal swordsman comes to life and does battle with the protagonist. The skeleton cannot be killed with the sword, but can be defeated by being dropped into one of the pits.

unique trap encountered in stage four, which serves as a plot device, is a magic mirror, whose appearance is followed by an ominous leitmotif. The protagonist is forced to jump through this mirror upon which his doppelganger emerges from the other side, draining the protagonist's health to one. This apparition later hinders the protagonist by stealing a potion and throwing him into a dungeon. The protagonist cannot kill this apparition as they share lives; any damage inflicted upon one also hurts the other. Therefore, the protagonist must merge with his doppelganger.

In stage eight, the protagonist becomes trapped behind a gate before he can reach the exit. In this stage the Princess sends a white mouse to trigger the gate open again, allowing him to proceed to the next level.

In stage twelve protagonist faces his shadow doppelgänger. Once they have merged, the player can run across an invisible bridge to a new area, where they battle Jaffar (once the final checkpoint is reached, the player will no longer get a game over screen even if time runs out, except if the player dies after the timeout). Once Jaffar is defeated, his spell is broken and the Princess can be save