In my experience, the preferred format for a U8 soccer game is small-sided, typically 5v5 or 6v6, including goalkeepers. This format allows for more touches on the ball, increased opportunities for decision-making, and a greater chance to develop both attacking and defending skills. The field should be smaller, as it's more appropriate for their age and physical development. The emphasis should be on fun, and the development of technical and tactical understanding rather than the match outcome. Remember, the ultimate goal is to foster a love for the game and help kids grow in their skills.