Here are the rules from the traditional game of Scrabble(tm). You will notice how Gnerudite includes these by default and allows you to expand on them and modify them to your liking.
At this point I should probable point out that Scrabble is a registered trademark owned in the United States and Canada by Milton Bradley Company, a division of Hasbro, Inc., and in Great Britain and everywhere else in the world, by J.W. Spear & Sons PLC., a subsidiary of Mattel.
You should have a gameboard, 100 letter tiles, a letter bag, and four racks.
Before the game begins, all players should agree upon the dictionary that they will use, in case of a challenge. All words labeled as a part of speech (including those listed of foreign origin, and as archaic, obsolete, colloquial, slang, etc.) are permitted with the exception of the following: words always capitalized, abbreviations, prefixes and suffixes standing alone, words requiring a hyphen or an apostrophe.
Place all letters in the pouch, or facedown beside the board, and mix them up.. Draw for first play. The player with the letter clesest to "A" plays first. A blank tile beats any letter. Return the letters to the pool and remix. All players draw seven new letters and each place them on their racks.