In Pokémon Crystal, you’ll find the Coin Case in the Goldenrod City Underground Tunnel. It will be located directly below the shop area where the Haircut Brothers appear.
The Coin Case is essential to play anything at the Game Corner in Goldenrod City, as you need coins to access the games.
Note: If you head to the Game Corner before getting the Coin Case, a guy will tell you that he dropped his Coin Case in the Underground Tunnel.
Coin Case Location (Step-by-Step)
If this is your first trip to Goldenrod City, then you will be coming from Route 34.
Upon entering the city from Route 34, head north until you see the Pokémon Center.
After that, make a left down the alley just behind the Pokémon Center.
Then follow the path around & downward.
If you walk past the guy with glasses, you’ll find the entrance to the unground area directly beneath him.
The building that you need to enter is on the right. It has a sign in front of it that says: “Underground Entrance”.
Once inside, walk down the stairs.
Once you’re in the tunnel itself, starting walking north.
You’ll run into a couple battles along the way, but they shouldn’t be too challenging.
Once you pass Pokémaniac Isaac, the item ball that contains the Coin Case is in a corner to the right.
With the Coin Case, you can now gamble at the Game Corner!
Where To Find The Game Corner
The Game Corner in Goldenrod City is very close to the entrance of the Underground Tunnel.
Simply turn around and head back up the same stairs that you walked down to get to the tunnel.
Then walk out of the building and start heading back north on the same path that you traveled earlier.
When you get to the top of the path you’ll see a building to your right with a sign out front.
This is the Game Corner, where you can play games and stack up coins for some pretty decent prizes.