How to Play Downstream

About Downstream, from BoardGameGeek:

Downstream is a puzzly 2 player card laying game where players create a river and attempt to enrich their own shoreline. In the game, players add cards to a growing river ecosystem; either extending the flow of water or tucked to extend existing banks. Cards extending the flow add scoring features to either shore while tucking cards means a missed opportunity to affect the flow of water. Players compete to achieve a varying set of objectives in each game, the resulting rivers having their own personality. -description from the designer