Coal to Core

About the game

Coal to Core is a mining and merging game played on two linked screens. It runs right in your browser, with nothing to install.

Dig Head down into the mine and dig through the dirt to collect ores. The deeper you go, the rarer the ores. Your bag has limited space, so choose what to dig and in what order. The mine has a new layout every time you go down.

Merge Return to the surface and drop your ores into the tub. When two matching ores touch, they merge into the next ore. There are 12 stages: Coal, Copper, Iron, Silver, Gold, Crystal, Amethyst, Sapphire, Emerald, Ruby, Diamond and, finally, the Star Core.

The Twist Ores go into the tub in the exact order you dug them, and you can see the next three. The order you dig in the mine is your plan for the tub. If ores stay above the warning line for too long, the tub collapses and the ores inside it are lost. Your bag and your Collection are kept, so you can keep going with a new tub.

Discover all 12 ores to complete your Collection. Each new discovery gives you extra bag space, and making the Star Core takes you to the ending. Progress is saved automatically, so you can play in short sessions.

Features

• Two linked screens: dig in the mine, merge in the tub
• 12 ores and Collection cards, from Coal to the Star Core
• Ores drop in the order you dug them, so plan ahead
• A tub collapse never wipes your run: your bag and Collection stay
• Auto-save, English and Korean, mouse, keyboard and touch
• Pixel art and sound effects made in code

How to play

1. Start Press Play to start right away in the mine. If you have a save, press Continue to pick up on the surface.
2. Dig Move the miner to dig down through the dirt. Dig a block with ore in it and the ore goes into your bag. The order you collect ores is the order they will drop into the tub. The Recent box at the top shows the last three ores you collected.
3. Return When your bag is full, "Bag is full" appears and any more ores you dig are lost. Press Return (R on the keyboard) at any time to go straight back to the surface.
4. Drop On the surface, aim over the tub and drop an ore. You always drop the ore at the front of your bag line, and you can see the next three beside it. After each drop, you can drop the next ore 0.5 seconds later.
5. Merge When two matching ores touch, they merge into one ore of the next stage. If the new ore touches another matching ore, they merge again in a chain, and chains earn bonus points.
6. Warning line If an ore stays above the red dotted line near the top of the tub for 3 seconds, the line starts flashing. At 5 seconds the tub collapses. Only the ores inside the tub and the current tub score are lost; your bag and Collection stay. Press "Keep going with a new tub" to continue with an empty tub.
7. Back to the mine Once the ores in the tub have settled and nothing is above the warning line, the Go mining button (M on the keyboard) unlocks. You can go down even with ores left in your bag; new ores join the end of the line.
8. Collection and ending Every ore you make for the first time is added to your Collection as a card, and your bag grows by 5 slots (your first Coal is added without a card). Make the Star Core, the 12th ore, to reach the ending. You will see your total play time, mine trips, tub collapses, longest chain and all 12 cards, and you can save a picture of your records with Download.

Controls

Ores always drop in the order you dug them.

Tips

1. Dig matching pairs back to back. Ores drop in the order you dug them, so if you collect two matching ores in a row, they drop one after the other and are easy to merge. What you dig, and in what order, is your plan for the tub.
2. Use the next-three preview. If the partner for the ore you are about to drop is among the next three, you can plan ahead: drop this one here, then the next one right on top of it.
3. Dig deeper for rarer ores. The ores you find change every 30 m. From 0 to 30 m you only find Coal and Copper, while Sapphire and Emerald appear only on the bottom layer, from 150 to 180 m, and they are rare. Below 180 m is solid bedrock that cannot be dug.
4. Make new ores in the tub first. Ores you have never made show up as Coal in the mine. Each new ore you make also adds 5 bag slots, so you can bring back more ores per trip.
5. Return as soon as your bag is full. Ores you dig after your bag is full are lost. There is no time limit in the mine, so choose what fills your bag, and once it is full, press R (or Return) to go straight back up.
6. A flashing line means you have 2 seconds. If an ore resting on the floor or on other ores stays above the warning line for 3 seconds, the line starts flashing, and the tub collapses at 5 seconds (from 4 seconds it flashes faster and a warning sound plays). Ores that are still falling are not counted, but a merged ore keeps the time its parts spent above the line. The timer only resets once the top of the ore drops back below the line.
7. Build chains for bonus points. If a freshly merged ore merges again within 1.5 seconds, the chain continues, and each chain step adds half of the base score. For example, a Diamond made on chain 3 scores 1,024 plus 1,024, for 2,048 points.
8. Keep big ores to one side of the floor. One Diamond is about two fifths of the tub's width, so two Diamonds fit side by side on the floor. Keep your first Diamond on one side and make the second one next to it, and you can go for the Star Core without stacking high.

The 12 ores

Merge two matching ores to get one ore of the next number. Only ores 1 to 9 can go in your bag.

FAQ

Screenshots