One of the most enjoyable things about developing a site like this is you get to look at a lot of different word games and figure out what makes them tick. Once you get past the cosmetic differences and gimmicks, most games still revolve around a handful of basic vocabulary challenges.
The first set of games involves pattern searching and word completion: given a partial set of the letters in a word, fill in the missing letters and guess the word. Solving these problems involves executing a fast pattern search against a list with enough words. This is the basic mechanism behind the hangman solver which we built. As an example of cosmetic differences between games, we were able to easily adapt this into a hanging with friend solver by adding a new scoring system and tweaking the seach logic.
The second set of games revolves around identifying which possible permutations of a set of letters are proper words. This is the basis for Scrabble (solver here) and it’s Zynga clone, Words With Friends (solver here). The same logic also works for a word unscrambler. Most scrabble variants involve some form of placing tiles on a board, modifying the universe of potential solutions through requiring a player to build off an existing word (more letters) and adding constraints around where tiles can be placed (empty spaces, adjacent tiles must form a word). Solving these challenges efficiently requires the player to transpose the letters in their hand into words. This is also where you generally need to start doing serious algorithm work around a solver: there are usually enough permutations of a seven letter rack that many naive approaches are computationally impractical.
The third broad class of word games in general use is a grid search, such as Boggle or larger n x n word searches. We built a version of this using Python as part of our Boggle solver. Computationally, this is a mix of a permutation search and pattern matching – you need to iterate through all the possible paths in a grid and spot situations where the word fragement matches the pattern of a known word.
I’ve seen a fourth model proposed but the gaming market hasn’t really embraced it: a blend of Scrabble and Poker. This involves building words from letters in your hand (a basic scrabble style permuation search) but incorporating mechanics to allow a player to control the relative “payoff” of hand via betting and bluffing. I suspect this game can really only be played pleasurably between players at a similar vocabulary level: adding betting mechanics allows players with a large vocabulary to both build better words and have better insight into the relative value of their hand. Eg. score more points and do a better job of identifying situations where they should increase their bet (or fold).
These three patterns dominate the commercial word game space, for both board games and mobile gaming.