Jar

Verified against the spelunky.ai port v0.1.10 on 27 October 2026.

It's carried and thrown like a Rock, but it breaks on whatever it hits hard, and a broken Jar sometimes has something in it: gold, a big gem, or a monster. Level generation leaves Jars lying in every area, and they have movement code of their own, which makes them fall and bounce a little differently from other items.

A Jar is picked up and thrown as any item is: crouching over it with empty hands and pressing the attack key lifts it, and the attack key throws it, at 8 pixels a step plus the player's speed, or up, or low along the floor ^{[3] [4]}. Its own code moves it: it falls 0.6 pixels a step faster each step until it's falling at 6 or more, and bounces off walls and floors as a Rock does ^[5]. It breaks when it:

• hits a ceiling going up faster than 3 pixels a step, hits a wall faster than 3 across, or lands faster than 3 ^[6];
• ends up inside a block ^[7];
• touches a monster or a Damsel while moving faster than 2 pixels a step ^[8];
• is hit by the Whip's crack (or a Machete's slash or a Mattock's hit, which the game counts as kinds of whip), a bullet or an explosion, or sinks into lava ^{[9] [10] [11] [12]}.

Breaking, it shatters into three pieces and rolls once for what's inside, each roll made only if the ones before it fail ^[13]:

In the clip, the player throws a Jar at a Snake: the Jar shatters on it and the Snake dies ^[21].

The Jar's own code decides what it does to a monster, and it isn't the code other thrown items share ^[22]. It picks the monster nearest it, as they do ^[23], and unless that one is invincible:

Either way, the monster takes three tenths of the Jar's speed, and the Jar breaks, on an invincible monster too ^[26]. A UFO that loses its hit point becomes a falling wreck, as from a bullet, rather than blowing up as it does for a Rock ^[27].

• Level generation, in every area: on each block that could have a Rock (outside shops, with open space above, away from the entrance, the exit and a golden idol), a 1 in 40 chance, once the Rock's 1 in 100 fails ^[28].
• The level editor's j tile ^[29].

The Jungle's graveyard room with the crystal skull has four tiles that the code means to make rising bones or a Jar, but its test is always true, so they're always bones ^{[30] [23]}.

• Whip. The crack breaks a Jar, and its code rolls for the contents, then destroys the Jar, which rolls again: a whipped Jar gets two rolls, and can let out two things, as does one a Machete or a Mattock breaks ^{[31] [13]}. In the clip, one Jar lets out a big emerald and a gold chunk ^[32]. The wind-up behind the player doesn't break one.
• Pitcher's Mitt. A Jar thrown with it keeps the Mitt's lighter gravity for good, as its own code only changes gravity in lava, so it flies far and flat ^[23].
• The screen. Most items stop once they're 16 pixels off the screen; a Jar's code has no such test, so it keeps moving until the level puts everything far off the screen to sleep ^{[33] [34]}.
• Exits. Carried through a level's exit, it's in the player's hands on the next level, whole: the old one is removed without breaking ^[35].

• A Jar breaks on the first monster it touches, so each one is a single shot; a Rock can be thrown again.
• A Jar only stuns a Caveman, a Hawkman, a Mantrap or a Yeti, where a Rock also takes a hit point.
• Whipping a Jar gives two chances at what's inside, where throwing it gives one.

• The Jar's movement code is a copy of the shared item code's, and keeps lines that only matter for other items: a Bomb exploding in lava, and an arrow being destroyed when it hits a monster ^{[36] [37]}.