The Sinnoh Underground returns from Pokemon Collesseum. The Sinnoh Underground is like an actual underground world where you can play games, meet others, create a secret base, and dig for rare items.
To go underground, you will need an Explorer Kit, which can be obtained in Eterna City from the Underground Man (house next to the pokemon center) . He will ask you do do certain tasks, and you will be rewarded for doing them.
You need to use the kit outside, and it will not work in buildings and caves.
You can build your secret base with a digger drill. You can obtain one from the underground man from doing tasks or you can buy one from Hikers. Some hikers will sell goods for decorating your base, others will buy treasures you have dug up in return for spheres. Spheres are the Underground World Currency. Others are trap sellers, where you can buy traps to slow down people.
You can mine for treasures and spheres. Just tap the screen and look for diamond shapes on the walls and look on your map. White diamonds on the floor are traps. You can deactivate them and take them by standing next to them and pressing A. Yellow diamonds on the walls are treasures you can mine for. Just stand next to it and press A. Use the tools to hit at the wall to uncover things. You can hit as many times you want until the wall collapses.
You can set traps so people dont steal your flag. Your flag is in your secret base. You can buy traps and deactivate others. Traps will only slow people down, but they will eventually be set free from them.
Capture the Flag:
Flags are in everyone's secret base. Stealing people's flags will remove rocks from your base that are in your way. Just talk to the Underground Man once you have stolen a flag, then go to your pc and remove them.
Once you steal 50 flags, you can remove all your rocks.
Sinnoh Underground does not connect on Wifi, so you need to be physically near someone to see them underground. The only way you can enter someone else's base is if they are near you.
The main menu of the underground is different.
Goods: That is where you can find your goods you purchased from Hikers
Traps: Where your traps are held, your digger drill is also there, but it is a once use only item.
Treasures: Your treasures you dug up are here. You can bring them in your normal bag to use them from the surface.
Card: This shows you stats
Return Up: Go back up to the surface
Here is a map of the Underground. It shows where Hikers are located.
credits to gamefaqs.com
and thinks ronjocox for reminding me where the map was from :)