Dark rubble landing off-centre

Verified against the spelunky.ai port v0.1.11 on 28 October 2026.

A block that breaks leaves three pieces of rubble around its middle. The Ice Caves' dark rock, and the mothership's hull, leave theirs off-centre, to the right of where the block stood and below it, because of a typo in the line that places them: rand(0-8), a minus where a comma should be.

The player breaks a brick with a Mattock, and its rubble falls where the brick stood. He jumps a pit and breaks a block of the Ice Caves' dark rock: its rubble comes out to the right of the block and below it, and falls past the block's edge ^[1].

A brick's destroy event puts each piece of its rubble at the block's middle, plus or minus up to 8 pixels:

    instance_create(x+8+rand(0,8)-rand(0,8), y+8+rand(0,8)-rand(0,8), oRubble);

The dark rock's has rand(0-8) in place of the second rand(0,8):

    instance_create(x+8+rand(0,8)-rand(0-8), y+8+rand(0,8)-rand(0-8), oRubbleDark);
    instance_create(x+8+rand(0,8)-rand(0-8), y+8+rand(0,8)-rand(0-8), oRubbleDarkSmall);
    instance_create(x+8+rand(0,8)-rand(0-8), y+8+rand(0,8)-rand(0-8), oRubbleDarkSmall);

0-8 is one argument, -8. rand returns a whole number from its first argument to its second ^[2], and the missing second is 0, so rand(0-8) is -8 to 0. Subtracted, it adds 0 to 8, and the rubble lands 8 to 24 pixels right of and below the block's corner, where rand(0,8)-rand(0,8)'s -8 to 8 centres it on the block. Both draw the same random numbers, so only the rubble's place differs. The mothership's hull has the same line ^{[3] [4]}.

Break any block of the Ice Caves' dark rock, with a bomb or the Mattock, and watch where its rubble starts. The replay of the clip's staged scene, a custom level, has a brick and a block of dark rock each over a pit. The brick's rubble starts over the brick's own place; the dark rock's starts 13 to 23 pixels right of its corner and 16 to 19 below it, and falls past its right edge ^[5]. In play, a bomb that breaks the hull of the mothership leaves the same off-centre rubble ^[6].

The spelunky.ai port reproduces it exactly: it's in docs/quirks.md's list of the 1.1 source's bugs ^[4], and the oracle's fingerprint of the replay pins every piece's place. No option turns it off.