Ghost (Classic)

Spawns:	• Any level except the first and last, at 2:30 • When retrieving the Crystal Skull • Destroying three or more Altars
Health:	Invulnerable
Damage:	Instant Death (Contact)
Stunnable:	No
Corpse:	No - Even if it could be defeated, ghosts are incorporeal by definition.
Size:	Large (2x2)
Notes:	• Passes through walls. • Turns ordinary jewels into diamonds.

The Ghost is the ultimate danger in Spelunky. It is not killable, it can not be escaped, and one touch is guaranteed death.
Fortunately, it is possible to make it through the entire game without ever seeing it.

Unlike many enemies in the game, the Ghost is more of an incentive than an obstacle. It exists to prevent loitering by greedy treasure hunters, and 'turtling' by the more pusillanimous of defilers.

Strategy

The Ghost is unkillable, and will pursue the Spelunker relentlessly, so the only 'strategy' possible is to simply run away.

There are three circumstances where the Ghost is summoned:

1. The first happens when the timer on a level reaches 2 minutes and 30 seconds.
   At 2 minutes, you're given a warning:
   "A chill runs up your spine! Let's get out of here!" as the level music progressively decreases in pitch.
   30 seconds later the Ghost spawns along with a distinct sound effect. You have two options at that point: Get to the exit... Or die.
   The Ghost does not spawn in this manner on the first or final levels of the game. It will also not spawn if you have the Hedjet in your inventory.
2. The second instance in which the Ghost can spawn is on a Restless Dead level. If a Crystal Skull appears on that level, picking it up will immediately cause the Ghost to spawn.
3. Finally, destroying an altar for the third time, and any time after that in a single game will immediately spawn the Ghost alongside making the level dark.

The Ghost disappears once he catches you. This is only of significance if you have the Ankh, in which case you will be revived on the same level and the Ghost will be gone. In this situation, the Ghost will not spawn again until you progress onto the next level. An associated glitch makes the HUD also disappear when this happens.

Ghostrunning

For the daring and agile, the Ghost can be used to generate extremely valuable Diamonds. If the Ghost passes over ordinary jewels (even if they are in the ground) it turns them into diamonds of a much higher value than what you would get for picking up the ordinary jewels. Doing this deliberately is known as Ghostrunning, and can result in astonishingly high scores.

Trivia

The Ghost may be a reference to the ghost from Spelunker, but it functions more like Baron von Blubba of the Bubble Bobble series, who operates as an invincible (but avoidable) enforcer of the stage time limit. Baron von Blubba is accompanied by an ominous theme tune, much as the Ghost in Spelunky warps the background music when it appears.

Removal with Mods

For those who resent the time limit on Spelunky's levels, there have been mods created for the game that remove the Ghost.
One example is Spelunky Un-Haunted - A recompiled .exe with one block of code deactivated.
This does not prevent the Ghost from appearing when picking up a Crystal Skull on the Restless Dead level, nor will it prevent the Ghost from appearing if you destroy your third altar, so effectively the only change it makes is removing the time limit in levels, allowing you to explore to your heart's content.