This game is included with only one Tiny Chao Garden: the one that is downloadable from Sonic Adventure DX. It can be accessed by clicking the white GBA at the top of the screen. The idea of this game is to find lost Chao by using hints given to you.
The game begins with Cheese asking Sonic to find a specific Chao. Cheese will provide Sonic with the name of the Chao, and nothing more. You are then given control of Sonic, and a two minute timer starts counting down.
You can move Sonic around with the Up, Down, Left, and Right buttons. As you explore the area, you will notice that there are a lot of Chao! You can't ask them their names, so how are you ever going to be able to find the right one? To do this, you will need to gather clues. You should see some glowing orbs floating in certain locations, just like the ones in the Adventure Fields from Sonic Adventure DX. If you walk into them, Tikal will talk to you and give you an important hint! These hints can tell you what direction the Chao is in, if the Chao can see Sonic, whether the Chao is on the grass or pavement, and what the Chao is currently doing.
As you receive more hints from Tikal, you will become increasingly more confident about which Chao is the correct one. When you feel sure enough, you should stand next to it and pick it up with the A button. Then, carry it back to the entrance where Cheese is waiting. If you brought the right Chao, several things will happen: Cheese will reward you with some rings; you will gain 10 seconds on your timer; and Cheese will ask you to bring another Chao back. The amount of rings that you earn starts at 5 and increases by 5 with each additional Chao that you successfully bring back! However, be careful. If you bring back the wrong Chao, then you will lose 30 seconds on your timer as a penalty! This is a huge amount, so it is recommended that you seek enough clues first.
The game ends when you find all the Chao successfully, or when you run out of time. No matter how you end the game, you will be returned to the Tiny Chao Garden with any rings that you managed to earn. You can earn up to 105 rings in total per game.