OK, so I'll give you a brief synopsis of my idea to give this whole thing context.

I just thought up an idea for a game called Goblin Mountain. You are a goblin, and you want to be the biggest, wealthiest goblin of them all and definitely not die.
The game's resolution mechanic, and method for generating dungeons, involves dominoes.

When you perform an action, you draw a "bone" (domino) from the bag for resolution. You assign one of the numbers on the domino as your good number and the other as your bad number.
You add your good number to your ability modifier to determine success.
Your bad number determines what mishaps result from your action. Higher numbers represent lesser mishaps (with 6 representing no mishap) while lower numbers represent more dangerous mishaps.

After your action, you place the bone on the table, adjacent to another bone, to represent a wall. The numbers will represent different dungeon features like doors, stairs, or traps. Goblins can 'mine' the walls, removing them from the board, to gain an ore.

My question for you guys is... how can I figure out floors?

Why not just make the "walls" tunnels instead? And mining just extends the length of the tunnel? Maybe do something with those "I mined to gain ore and extended this tunnel" pieces...like "treasures" for the first goblin to get to them?

Use different colored dominos, or use 9s, or 12s to represent a new floor with double sixes (9s, 12s) being a way "up" and double oughts being a way "down"?