Players use developmental measures in the form of different cards to protect houses on a map against flooding.
Each round you gain income to pay for these measures and new cards. On top of that, there is an event card affecting all players. At the end of each round different houses along the rivers are flooded in certain patterns that are determined by dice roll. Every house that wasn't protected by you specifically (multiple people can protect the same house) gives you one negative point.
After 6 rounds you want to be the person with the least amount of negative points. Additionally, there are win conditions for having ecological and aesthetic points on your measure cards. Finally, after the end of the main game every player gives a speech about their protection efforts. Everyone then votes on the best speech, which is the third component for determining who wins the game.