The bonus map for the arctic zone in Terra Nil goes by the name Polluted Fjord. There are no fissures or lava this time around, but there are still plenty of ways to fill the map with the rocks needed for the lichen biome.
However, the first challenge is to locate all the rocks, riverbeds, and other useful terrain features since the map begins with nothing visible aside from a polluted ocean and dirty snow. Terra Nil players can't rely on lava or geothermal plants to generate the heat needed to melt snow or warm the atmosphere, but there are other ways to reveal the landscape.
Stage 1: Snow Melt
There isn't much to see at the start of the Polluted Fjord map. In every random map there's an ocean inlet to the southeast and highlands on every other edge, with nothing in between except a frozen landscape. The tier 1 buildings include the following:
- Turbine
- Tidal Turbine
- Toxin Scrubber
- Irrigator, Solar Amplifier
- Water Pump
- Calcifier
The map also comes with all four climate buildings:
- Cloud Seeder
- Combustor
- Dehumidifier
- Flash Freezer
The ocean inlet has four spots deep enough to place a Tidal Turbine. Players will have to do so, since there are no rocks for regular Turbines. However, that all changes as soon as players set down their first Solar Amplifier. Just like the Geothermal Plant, the Amplifier will melt all the snow in a radius around it. This will reveal not just wasteland and ash tiles, but also rocks and dry riverbeds. Players can then build Turbines on the rocks, hook up more Solar Amplifiers, and expand the melt inland.
Still, the cheapest way to reveal the map is to trigger the snow melt by reaching 0 °C. To do this, players should melt one corner of the map, cover it in greenery, and then burn it all with a Combustor or two. Finishing off this stage will go much faster once the snow melts since the map is covered in rock tiles and ash.
Stage 2: A Rocky Road
The tier 2 buildings in this biome are:
- Monorail Node
- Arboretum
- Biodome
- Algae Greenhouse
- Rock Hopper
- Excavator
After filling all the rivers in the first stage, players may have too much humidity for the tundra biome. The Dehumidifier can fix that. The dry grass it produces is perfect for burning with a Solar Amplifier to create the building husks and ash needed for the Arboretum and the forest biome, just like in the River Valley.
Once the tundra and forest biomes are finished, players should start creating rock tiles using Calcifiers. There are plenty of rivers and the Calcifier has a good radius, so this job will go by quickly. However, players should create these rocks before triggering the snowfall goal, because the snow will freeze land tiles to snow and turn the rivers into ice sheets. Calcifiers can't sit on ice, and they can't turn snow tiles into rock. This means that if players don't create enough rock tiles before the rivers freeze, they'll have to restart the stage.
One other thing to watch out for is to avoid creating too much kelp forest. The fjord is only so big, and kelp tiles don't count as ocean tiles when using the Animal Observatory to find marine animals.
Stage 3: A Speedy Clean
The tier 3 buildings are:
- Airship
- Recycler Station
- Recycling Beacon
- Recycling Silo
- Animal Observatory
Just like the Volcanic Glacier map, there should be plenty of rocks to set Monorail Nodes on, and so cleaning up shouldn't be hard. Players may have trouble reaching some of the highlands along the edges of the map, especially after the rivers freeze, but the Rock Hopper can help if nothing else works.
Terra Nil is available now on Android, iOS, and PC.