For the Sega Dreamcast, Sega made the first Sonic game for the system: Sonic Adventure (1998).
Sonic the Hedgehog saw Dr. Eggman summon a monster known as Chaos and Sonic realized that the only way to stop Chaos is to get all seven Chaos Emeralds before Eggman does.
The game lets players play as Sonic, Tails, Knuckles, Amy Rose, Big the Cat and E-102 Gamma in six different story modes before the conclusion of the game.
The game was revolutionary for the short lived console it helped create a sequel, Sonic Adventure 2 (2001) and inspired Sonic Heroes (2003).
Sonic Adventure is perfect to play with your kids.