When writing or translating an operation manual for software (including game software) or hardware users are mostly addressed by the polite form "Sie". Increasingly however we can also find manuals where the "Du"-form is used.
In what context could it be appropriate (or even better) to address users by the "Du"-form, and in what context is the "Sie"-form mandatory?
The simple answer is: "Sie" is always appropriate unless you are addressing a child.
However, there are a lot of situations where the "Du" is more common today; this includes most usages in forums, blogs or social networks, leading to the belief that it is accepted for general use.
Some companies use it as a form of corporate identity. Ikea and Apple come to mind with their notorious "Du" in ads and I think also in the quick start manual of Apple devices (the short paper thing that is in the box). The real manual, however, addresses the user as "Sie", so even in "Du" companies, it seems that this is more appropriate in operation manuals.
Know your audience. In most fields, "Du" is not apprioriate in manuals. Exceptions are typically lifestyle products, but even there you'll find the "Sie" in the actual manuals. When addressing children, "Du" is fine. This can also be used to distinguish between parts for the children and parts for the parents.
German board game rules often employ a form that has not been mentioned yet:
Der Spielplan wird wie in der folgenden Illustration aufgebaut. [...] Jeder Spieler erhält 5 Gold und 2 Aktionskarten.
This is a neutral form that uses neither "Du" or "Sie", nor "man". It is not really appropriate for a technical manual, however ("Der Benutzer drückt auf die PROGRAM-Taste." (; ). Interestingly, in a FAQ for such a game, you'll likely encounter "man": "Kann man nach einem Spielzug eine Karte abwerfen?"
"Sie" is mostly used in a formal context, if you are writing a manual addressing older or business readers you would use that. "Du" could be used to address younger readers or gamers.
It's possible as well to avoid using either "Du" or "Sie" by indirectly talking to the user or using "man". eg "Du kannst das auf diese Art machen" and "Sie können das auf diese Art machen" is like "Man kann das auf diese Art machen".
Additionally to Du and Sie afaik its quite common to use Wir in special parts of a manual, dissertations, thesis, tutorials.
But then you should only use it when e.g. writing a step by step guide for setting up a video recorder, a lab experiment, derivation of formula, installation of firmware/software, where no options arise.
Wir können A oder B jetzt tun
is not often used, here you would better use Sie.
If you explain specific functions etc. you should of course use Du oder Sie.
I personally quite like the Wir, doenst make you feel so lonely reading a complex instruction guide and you dont think every failure you make is only yours ;)
In a official manual/pdf of a serious company i dont think Du is good style and i never saw this.
I prefer "Sie" and find it easier to understand. The many comments and suggestions were interesting, however when the objective is to clearly understand what needs to be done, using "Sie" seems to me to be the best choice.
