From Wikipedia:
Mario vs. Donkey Kong: Minis March Again! (マリオvs.ドンキーコング ミニミニ再行進! Mario Bui Esu Donkī Kongu: Mini Mini Saikōshin!) is a puzzle video game for the Nintendo DSi. Announced at the Electronic Entertainment Expo 2009, it is the third game in the Mario vs. Donkey Kong series. It is the first DSiWare game to feature a level editor in which players can create custom-made levels and send them to players on other devices via a wireless Internet connection.
Mario vs. Donkey Kong: Minis March Again! features puzzle-solving gameplay, which was made popular in the previous two games in the series. Just as in the game Lemmings, Mario must lead his Mini-Mario toys to the end of the level. Like with Mario vs. Donkey Kong 2: March of the Minis, players do not control Mario but instead miniature wind-up versions of Mario, Princess Peach, Toad, and Donkey Kong—referred to as "Minis"—in order to rescue Pauline from the game's antagonist, Donkey Kong. In each level, players must get all their Minis to the end of the level at a designated exit while avoiding obstacles and enemies (mostly consisting of enemies from the other games in the Mario series).
One notable difference in this game and the predecessor is that all of the end of level bonuses are now required. In the previous game, extra points were earned by getting all Minis to the exit, getting them to the exit with no long time intervals between any two Minis, and getting them to the exit without stopping any of them. In Minis March Again, the door is boarded up and the player fails the level if any Minis don't make it to the exit within a few seconds of another Mini getting to the exit, and none of the minis may be stopped or turned directly by the player. Only items and obstacles can be used to control their direction.