Streams consists of pens, score sheets, and a deck of forty cards (bakelite tiles in the second edition); the cards are numbered 1-30, with two copies of #11-19 and one wild. Game play is similar to Bingo in that someone draws a card and everyone must then mark that number on her scoring sheet. This sheet contains a line of 20 spaces to be marked, and while these spaces can be filled in any order, if she can place them in non-descending order identical numbers placed side-by-side don't break a stream she'll score points. The longer the stream of ascending numbers, the more points she'll score.
Once twenty cards have been drawn and the scoresheets filled, players tally their points for each stream of non-descending numbers, and the high score wins.
The second edition of Streams includes normal and expert rules.