Second-guessing search-engine bots is a tricky business. At the very least, the image ought to have its ALT text set to the game title, although arguably people browsing the maps with images disabled aren't going to enjoy them much.
However, Google doesn't like to search ALT/TITLE text (it indexes it but excludes it from search results, probably due to SEO abuse). It seems happier if you have some semantically-correct header tags (<h2> etc) containing the titles, and more so to have the right sort of things in the page title. Obviously the current static HTML site approach makes the latter difficult to achieve, but I don't see any reason not to have the former as per osrevad's suggestion.
I think it's this simple syntax, and page titles, that give my site the win for Google Images searches for "sonic maps" and "sonic the hedgehog maps".