Evolution is a game mode in Battlefield Vietnam.
In an Evolution game, you play the first map of a selected pair. When the first battle ends, the next one starts automatically. The players will keep their scores and team assignments. How the initial control points and ticket ratios are set up will depend on how well each team did in the previous level. If both teams were neck and neck at the end of the first battle, the second one will start off balanced. If one team was losing badly on the first map, they will have an uphill battle in the second.