Divide into two teams. They should be as even as possible. Each player will be given a letter of the alphabet drawn like a scrabble tile on a piece of paper. Letters should be big and fill the whole piece of paper and most importantly, each paper needs to have the same value written on it as a scrabble tile. For example an "A" would have a value of "1" written a bit smaller in the lower right hand corner of the paper. See below for scrabble tile values. Papers are taped to the chest of each player (or to their back if you prefer to make it harder). Each team should be given the same letters of the alphabet with a good mix of vowels and consonants. A good approach might be to estimate how big each team will be (let's say for example each team will have 8 players) and choose an eight letter word such as "radiator".
The host needs to also write "normal word score" "double word score", "triple word score", "double letter score on letter 2", "triple letter score on letter 3" etc. on multiple pieces of paper and stick them in a hat to be drawn. You can use any value for double and triple letter scores so you might write "double letter score on letter 5" as opposed to letter 2. You probably want to have 7 or 8 different options in the hat.
To start each round, the host draws a slip of paper from the hat and reads it to the teams. Each team then huddles and agrees on a word using the letters they have on each member of the team. After one minutes the host says "line up" and each team must form the word they chose. Just like in scrabble, you do not have to use all your letters and may choose to only use 2 or 3 letters.
Each team is scored based on their letter values and the rules on the slip of paper drawn by the host.
The winning team is the team with the most points when you decide to quit, or the first team to a designated value such as 100 points.