Upwords was designed by Elliot Rudell and published Milton Bradley. Similar to Scrabble, except that players can stack letters on top of other words. The game's scoring is well balanced in that players get more points for words if all the letters are one layer, but they get more points as tiles get higher since you score for the tiles in your word and the tiles under your word.
Since Upwords lacks bonus squares like Scrabble, there have to be extra rules to keep people from capitalizing on other people's words and they do this by disallowing plurals that simply add S as well as other similar rules. Another aspect of the game is that as tiles pile up, the values increase giving it a feeling of trying to reach the top (fifth) layer because then each tile there is worth five points a piece.
Originally, Upwords was played on an 8x8 square board, which many players felt to be cramped relative to Scrabble's 15x15 grid. Newer Upwords sets come with a 10x10 square board, which allows for much more comfortable play.