kiln/kiln-core/src/scripts/gem.rhai

// Built-in script for the `gem` archetype (see kiln-core/src/builtin.rs).
//
// A gem is a collectible: it is solid, so walking into it fires this `bump()`
// hook. We bank the gem and `die()`, which clears the cell — so the move that
// bumped us completes and the player ends up standing where the gem was.
fn bump(me, dir, by_player) {
    if by_player {
        alter_gems(1);
        die();
    } else {
        move(dir.opposite, false)
    }
}