How do I see if there's a different language version of the same game page in the wiki?
I don't know if there is an automated tool for it, but you can check by editing URLs directly. Foreign-language pages have the same name with an added prefix:
German pages are de-WHATEVER
French pages are fr-WHATEVER
Spanish pages are es-WHATEVER
For example, Bharg is at game:bharg, and the Spanish translation is at es-game:bharg
I have looked around the docs and there doesn't seem an obvious way to list possible translation in an automated way. Translations are so few and far between that some signal should be hoisted where they actually exist. I would not edit a URL manually to see if a translation exists.
One possibility would be to use the site structure features of Wikidot. Translations could be played as children of the original articles. A game page skeleton would include the names of its children.
There's a section of the sidebar for "Languages besides English". The first of those was set up by Jorge, who started the wiki. The Spanish link (which he set up) is a list of all the pages that are in Spanish. Other languages have been added as contributors have come along.
The French link is to a welcome page that lists all the games with French rules at the bottom.
The German one links to a welcome page that doesn't have such a list. Following the pattern for the French welcome page, something like:
[[module ListPages category="de-game" order="titleAsc" ]] * %%linked_title%% [[/module]]
I'm not opposed to something more thorough, but I don't really know much about it. Would changing it so that translated games were child pages require moving all of the game pages?
The page http://decktet.wikidot.com/de-all-games exists and is linked from the German welcome page via the text "die ganzen Spiele". I can't look at the source but the page seems to update automatically with new de-game entries.
Any article can be delared as a parent of another without breaking naming conventions. See http://community.wikidot.com/forum/t-287069/ It is "heavy work" when done as an afterthought but still doable with the low number of translated pages here.
I tried that with the Spanish page for Bharg. Although the breadcrumbs navigation works to connect the translation back to the English version, there isn't any visible connection leading from the English version to the translation.
Adding [[module PageTree]] would make the link, but without any explanation. Often the non-English pages have the same title.