A pun on the word
upwards, Upwords is a
crossword game in which you can change an existing letter on the board by playing another letter
on top of it.
The scoring is very simple; the score for each letter is the number of letters in the stack containing that letter, except that words placed completely flat on the lowest level score two points for each letter. Note that there is a limit on the height of stacks -- no more than five letters high.
The original game uses an 8x8 board and 64 letter tiles which are more consonant-heavy than the distribution in Scrabble. I have heard of but not seen an expanded version using a 10x10 board and more letter tiles.