Good games for eight year olds include, but are not limited to, Super Mario, Super Mario 2, Super Mario 3, Sonic the Hedgehog, Tetris, almost anything on the Wii.
Tag is an old-school and simple game. But it can also be added with twists and variations to your desire, like having two "its" at the same time for twice the fun. For a relaxing game, you can try guessing games like charades.
If you're talking about Videogames, You can try getting them any games based on Nickelodeon shows, such as the Rocket Power, Spongebob ones. Those should be suitable for them. If you're talking about board games and such, try checkers. They should love them.
