Arrow Trap

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

An Arrow Trap looks like a carved stone block set into a wall, with an opening facing along a corridor. It fires an arrow the first time anything moves in front of it, and never again. The arrow takes 2 hearts from the player, as any fast arrow does, and hurts monsters as a thrown arrow does. On a dark level the traps are lit, glowing so that the player can see them.

A trap has a sensor: an invisible strip in front of it, made one step after the trap, that reaches from its face to the first block in its row, but no farther than 6 blocks for a trap facing left and 5 for one facing right ^{[4] [5] [6]}. The two directions' code measures the strip differently, which is where the extra block comes from: the left-facing one counts up to 96 pixels from the trap, the right-facing one up to 80 from the block in front of it.

Anything in the strip that's moving sets the trap off: the player, a monster, an item, a piece of treasure, a pushed block or a Boulder. The player also sets it off near the end of his drop from a ledge into a hang from it, even without moving ^{[7] [8] [9]}. Standing still in the strip doesn't.

When it's set off, the trap fires an arrow from its face at 8 pixels a step (240 a second), plays its sound, and its sensor is destroyed, so it never fires again ^[10]. The first clip shows the player standing in a trap's strip, three blocks from it, without setting it off; when he takes a step toward it, it fires, and the arrow hits him.

An arrow falls as it flies, and on the ground it loses 70% of its speed each step, as any item does ^{[11] [12]}. A trap fires from near the top of its block, so its arrow along a floor lands after about three blocks and slides on too slowly to hurt. The second clip shows a player setting a trap off from the far end of its strip: the arrow drops onto the floor and stops short of him.

The trap itself hurts nothing: its arrow does, the same arrow the Bow shoots, while it's moving fast.

An arrow that kills the player is counted in the end-of-game statistics' arrow row ^[15]. The check takes the arrow nearest the player, not necessarily the one touching him ^[16].

Level generation turns some of the plain blocks of the walls into Arrow Traps, after it has placed everything else:

A block only qualifies if it isn't in a shop, is more than 48 pixels from the entrance and not within 144 pixels of it on the same row, and has a block behind it and two open blocks in front of it: it faces left if the block to its right is solid and the two to its left are open, else right if the opposite holds (a right-facing trap's check also takes in the first pixel of a third block) ^[19]. On a dark level, the trap made is the lit kind ^[20].

Arrow Traps are also:

• In the Sun challenge room, a bonus room reached from the high scores, whose traps fire every 100 to 200 steps whatever is in front of them, while the player is alive ^{[21] [22]}.
• In custom levels, as the level editor's tiles < (facing left) and > (facing right) ^[23].

• Use up its arrow. A trap fires once, at whatever moves first: a Rock or any other item thrown through its strip, a monster walking by, or the player stepping in at the far end, where the arrow lands short.
• Destroy it. A trap is a block, and a Bomb destroys it like one. One destroyed before it has fired leaves its arrow lying where it was ^[24]. The third clip shows a lit trap firing at the player as he drops down a ladder across its line, taking two hearts, and a bomb laid beside it destroying it.
• Stand still. Standing in the strip doesn't set it off, but taking a step does.

• Boulders set off the traps they roll past, as the Boulder's clips show ^[25].
• The Bow collects a trap's arrow, once it lies still, like one of its own ^[26].
• Light. A lit trap counts as a light source on a dark level, as a lamp or a tiki torch does ^[27].

• The traps were first meant to watch along their row on their own: their step events still hold a motion check that would fire an arrow at the first moving thing in line, commented out. The sensor objects replaced it ^[28].
• Both kinds have an alarm, never set, that would fire a slow arrow to the right at 5 pixels a step, from either side: a left-facing trap's would come out of its back ^{[29] [30]}.
• An unused object, oTemp, is an earlier arrow trap that plays a sound the game no longer has ^[31].