Part one in the series of how to translate for games - parts 2 and three will be coming in the next few days. Thanks to our contributer who wishes not to be named for NDA reasons.

Some points on how to write for a game AND allow for a relatively trouble-free translation:

a) Use short sentences.
(Otherwise your customers won't be able to understand them.)

A rule taught to journalists is that the majority of the mass market is unable to handle sentences over 150 characters in length; that is, to read the sentence and comprehend its contents at the same time. (This is the rule of thumb for German, and the reason why tabloids never have sentences that run longer than 5 lines in 30-char column width.) (I doubt that the average population in English-speaking countries has much better reading comprehension.)

(If you doubt these, look at the latest PISA results. Almost 40% of the pupils in vocational schools have reading difficulty, or are unable to comprehend longer texts.)

Also, sentences that are short in English may run longer in other languages. In the current project, we had a sentence of 153 characters in English which ran to a whopping 435 characters in German - and the translators had not split it up into shorter sentences because they had been repeatedly urgend to "preserve the style" of the source text.

b) Don't waffle. (Otherwise users will click away the text instead of reading it).

It's frustrating to go through a game and take 100 hours to play - if this is simply because 2/3 of the game are spent looking at very long sentences, inane dialogues, the 25th book describing some obscure element of the game world in 3 pages of text, and the rest doing boring combat sequences and inane puzzles aimed at three-year-olds.
(But then, maybe it's just that I'm frustrated because I expected better from the current project.)

c) Avoid ambiguity. (Otherwise sentences will not say what you intended them to.)

Ambiguity doesn't translate well, it usually won't work in other languages. And translators, when faced with a choice of two meanings, will almost always pick out the wrong one.

d) Spell it out for the translators.
If you use ambiguity, innuendos, slyly dropped hints or similarly clever language tricks, describe them in the "comments" column of your translation tool. If you don't, the translators won't get them, and the translation will be literal (which won't always work in other languages.)

e) Finalize the text as much as possible before having it translated. (Updating translations is not nice. Re-recording is expensive.)

Finding that part of a dialogue has been rewritten can be a nightmare for the translator, who will double- and triple-check for consistency (e.g. changing "Have you any interest in this?" to " Are you interested in this?" may cause concatenation if another string, the answer, is "Yes, I have." There are different approaches to clearly marking such dialogues - either by using a translation database like LocalizationStudio, or by writing custom tools that allow the translator to "play" through (multiple-choice) dialogues.