Like a crossword puzzle, your island is overlaid by a virtual grid. Each grid cell can hold a letter. Here are the rules that determine how you build over the grid:
Last but not least, you need to have sufficient materials to build the desired word. Note that the interconnect letters do not consume any resources. Keep in mind that some letters (e.g. J) are much costlier than others (e.g. S). The game Word Builder has indicators that show you resource costs and word validity. If a word cannot be built, its outline in the game window will be shown in red.
Lets look at some examples to make all this concrete. Each example shows how the rules work by giving you a valid situation on the left, and invalid one on the right. There are two players in each example: blue and red.
Above left, all words form valid interconnections, and there is no side-to-side contact between player letters. Above right, you can see that PASS and SACK do not interconnect in a manner that forms a valid word. Moreover, the blue player letters touch those of the red player.
Above left, all words are packed very densely. That is ok as long as they form valid interconnections. Above right, some words formed by interconnection or adjacency are not valid (e.g. IOO). Also, the blue player is repeating a word that already exists in the game (LIP and LIPS are considered the same word).
Above left shows a valid way to continue building into new territory over a bridge (stairs work in the same manner). Above right, the blue player cannot build over the bridge. Its word is not adjacent to the bridge end. Also, there is an opponent word on the other side that blocks further expansion.
Unlike some games that make a big deal out of spelling rules, your success in Word War III does not require you to spell obscure words such as "SYZYGY". All you need is a good sense of how to organize your settlement. What's important is to have the right mix of letters at the right time (and to put them at the right place). In every situation, there are multiple goods words you can use, most of which are just plain English.
This being said, the game will not let you type anything. Ultimately, it is the game dictionary (compiled based on a survey of modern and classic literature) that determines what is a valid word. The spelling rules behind the dictionary are simple:
Remember not to be intimidated by the computer AI spelling complicated words. If you can too, fine. If you can't, be assured that good gameplay strategy will beat good spelling anytime.
The game Word Builder tool features a number of indicators to make it easy to build good valid words. Building takes place in two stages:
Stage 1: Word Input. Once you click the "Build" button, the Word Builder pops up, and your pointer is placed in the word typing box shown above. Type your word in the box or use the small virtual keyboard. As you enter your word, it is continuously validated against available resources and spelling. If the spelling is not valid, the indicator LED will turn red and you will not be able to move to the next stage.
If there are not enough resources, the LED will turn yellow, but you will be allowed to move to the next stage. This is so because the actual resource use is determined in Stage 2, based on WHERE you wish to place the new word. Stage 1 is just a first-pass validation of the word itself without regard for its position.
Stage 2: Word Placement. If you move the pointer out of the input box, the Word Builder will automatically move to Stage 2, where you place the word into the game viewport interactively. As you move the mouse, the word preview will move to different possible building locations. If the word cannot be built, it will be highlighted in RED. You can also see the actual resource consumption for building at the current location. LEFT-CLICK to build, and RIGHT-CLICK to change building orientation between left-right and up-down. If you left-click and the word cannot be built, you will get a message telling you the exact reason for it.
Sometimes, you may be stumped by what word to build. The Alerts Panel has a tab of word hints, that will suggest words that are appropriate for the current game situation and settlement configuration. The selection changes every time a new word is built.
Likewise, the tab of letter hints shows you which types of buildings you might need the most, given the current game situation. Go ahead, and give it a try. Learning by the example is a great way to master the game.