You've joined a hot air balloon festival in which the goal is to go higher than your opponents. Dump as many sandbags as you can — and try to gain rockets as well! — to send yourself higher and higher to win.
Sandbag is a trick-taking game of avoiding tricks, manipulating trump, and reconfiguring your hand of cards. In each of the three rounds, you configure your basket with two face-up cards; the most common color among all players' cards is the trump suit. Each trick, players either play from their hand, play a sandbag (to sluff, that is avoid winning the trick), or play one of their opponents' face-up cards. During the round, it's possible for the trump to change as the number and kind of face-up cards are exchanged for face-down sandbags. Five rocket cards worth negative points are in play each round, and you want to win these while avoiding the sandbag cards because in the end the player with the lowest score wins.