This game is included with only one Tiny Chao Garden: the one that comes with Sonic Pinball Party. It can be accessed by clicking the white GBA at the top of the screen. The basic premise of the game is thus: you must match coloured balls to make them disappear before they reach the bottom of the screen.
When the game starts, you will see a blank board covering most of the screen, with a Chao standing at the bottom in a purple area. Red and green coloured balls will begin to descend from the top of the screen. You must act quickly, before they get to the bottom!
You can move the Chao on the ground by using the Left and Right buttons. You can fire a red ball upwards by using the A button, and you can fire a green ball upwards by using the B button. You need to throw balls so that they touch other balls of the same colour. When 10 balls of the same colour are touching, they will disappear! Any balls that were underneath them will move upwards. Keep doing this to prevent the balls from reaching the bottom of the screen.
There is a trick that you can use to clear balls faster. If you shoot a ball so that it traps one or more balls of the other colour, with a ball of the same colour on the other side, then all of those trapped balls will change their colour. For example, imagine that there are three green balls positioned vertically, with a red ball above them. If you shoot a red ball underneath them, then the three green balls will be trapped between red balls; they will then turn red themselves.
Occasionally, you will see rings caught between the coloured balls. If you can clear away the balls underneath a ring, then that ring will start falling down. Move the Chao to collect it before it falls past the bottom of the screen, or it will be lost.
If you manage to survive long enough by clearing balls away without them reaching the bottom of the screen, then you will eventually move on to another stage. The balls will start again at the top of the screen, but they will descend more quickly than the previous stage. This means it gets harder and harder. Be careful!
The game ends when one or more balls descend into the purple area at the bottom of the screen, where the Chao is. When this happens, you will be returned to the Tiny Chao Garden with any rings that you managed to collect.