Brick Wall
Mortar is just the absence of brick if you think about it hard enough ᕙ(⇀‸↼‶)ᕗ

| Grid | Code Size | Leaderboard | Cycles | Leaderboard | Date |
|---|---|---|---|---|---|
| 15x15x15 | 63 | #56 | 9.907 | #2082 | 2026-02-23 |
Solution
v=y-1 return y==-7 and 2+(((x+1)//3+(z+1)//3)%2)*10 or z*z<4 and y<5 and(v%4*((x+(v&-4))%8)==0 and 3 or 7)
How it works
Two parts: a tiled floor and a brick wall.
The floor (y==-7) divides coordinates into 3x3 tile blocks using integer division //3, then colors them grey or darkblue based on whether the tile sum is even or odd. Classic checkerboard, just at a bigger scale.
The wall (z*z<4 and y<5) is where the fun is. Bricks are 8 wide and 4 tall, with every other row offset by 4 (the classic staggered pattern). We get that offset with v&-4, which rounds y-1 down to the nearest multiple of 4 using our favorite bit-mask trick. Add that to x, mod by 8, and you’ve got the vertical mortar lines.
The sneaky bit: instead of checking horizontal_mortar or vertical_mortar with an or keyword, we multiply them together. A product is zero when either factor is zero, so v%4 * bx%8 == 0 catches both mortar directions in one shot. Saved us 2 tokens over the or version!