Gold coins, or just gold, is an in-game currency. It can be spent on various improvements, such as increasing the level of traps or the number of master keys.
Also, gold is needed to improve the throne and skip the dungeons of players that you do not want to break into.
There are three ways to get coins:
In the centre of your dungeon is the gold mine that constantly supplies you with coins. Upgrade your Gold Mine Capacity and Production Speed in the upgrade menu (tap on the castle icon in your dungeon or simply swap downwards) to increase the income.
2. Collecting skulls
When somebody dies while attacking your dungeon, they will leave a skull in place of their death. Collecting these skulls by tapping them gives you extra gold.
Upgrade your Skull Gold Bonus to get more coins for collecting skulls. This is especially effective when you have a good defense.
3. Selling gems
If you don't have enough gold, you can sell one of your gems. To do it, tap on it and drag it to the lower right corner of the screen. The confirmation window will appear. Tap "Yes".
Please note, that this action is irreversible. You will lose rating points the sold gem had. Gems with the lowest rating are sold automatically when an inventory is full (excluding Unique Gems).
If you don't have enough gold to upgrade something, you can spend blue orbs instead.