Expanding

Expanding is the act of occupying an empty Dungeon in the Overworld.

Criteria
Once the Underworld Control technology is researched, players may begin to occupy empty dungeons. Players may only occupy one new dungeon every 10 overlord levels, which are gained by collecting Experience.

Process of Expanding
To occupy a new dungeon, a player must select a mountain from the Overworld and click "Occupy" on an unoccupied dungeon within. A player may choose to occupy a dungeon without surveying it first, but he/she may find undesirable mineral nodes.

Strategy
Depending on a player's room upgrades, he/she will gain 10 levels every few weeks. The fastest way to gain experience (and therefore further dungeons) is to: 1) Upgrade all vaults to level 2. 2) Upgrade all vaults to level 3. 3) Upgrade all Dens to level 3 (this doesn't give additional experience; rather, it adds one more goblin to the dungeon which will helps mine resources) 4) After acquiring the necessary research for the required furniture, upgrade all Mine]mines to level 5 and vaults to level 4. This will likely be the extent of your progress by level 30. 5) Upgrade additional rooms to level 5. Each level 5 room generates 1 XP/hour.

Choosing Expansions
Due to only having a few goblins for surveying at low levels, surveying your mountain and adjacent mountains before reaching level 10 will give you a wider variety of choices when an expansion becomes available.

At the bare minimum, a dungeon should include both Iron and Crystal, or it will require many shipped resources for upgrades. A preferred dungeon will also include Primordial Earth for faster room upgrades and steel ingots, which are used in furniture and room upgrades. Any dungeon that includes Iron, Crystal, Primordial Earth and any additional resources besides gold (which all dungeons have) would be a superior 2nd dungeon. It is not necessary to take dungeons with only higher materials as a second dungeon or progression will be slow. Significant amounts of Primordial Earth, iron and crystal are needed at level 10.

While searching for further dungeons, keep in mind the travel distance and mineral nodes in each dungeon. A dungeon filled with high level resources, such as Diamond may not be useful as a third dungeon, but it will come into use for a fourth or fifth dungeon. The new survey report tool located in the "Reports" section will help players find surveyed dungeons with desired minerals.

It is also recommended that your third dungeon has Iron, Crystal, and a Primordial element. Iron and Crystal will become sparse if it is not present in a third dungeon as it will be used for upgrades and training creatures. By level 30 and 40, having Iron and Crystal in a dungeon will be less of a requirement. Players will be raiding both settlements and players more often at these levels and building up iron and crystal through raiding. By this level, players will have further technologies that increase mining rates, higher level mines, better furniture to increase mining rate, and additional goblins, so the rate at which you produce Iron and Crystal from the same dungeon will increase significantly.

Use of Expansions
Once you reach level 20, you may want to start looking towards specializing your dungeons for the future so that dungeon tiles are used effectively. A level 5 room takes up a lot of space (25 tiles); having level 5 rooms of each type is impossible, and having the same level 4 rooms in each dungeon limits experience growth.