Streams (a.k.a. 20 Express) consists of pens, score sheets, and a deck of forty cards (or bakelite tiles, depending on the edition); the tiles are numbered 1-30, with two copies of #11-19 and one wild. Game play is similar to Bingo in that someone draws a tile and everyone must then write that number on her scoring sheet. This sheet contains a line of 20 spaces to be filled, and while these spaces can be filled in any order, if she can place the numbers in non-descending order – identical numbers placed side-by-side don't break a stream – she'll score points at the end of the game. The longer the stream of ascending numbers, the more points she scores.
Once twenty tiles 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.