The stories we play and write in fall within the Medieval Fantasy subgenre and may include elements of high or epic fantasy, heroic fantasy, court intrigue, and even romance. The setting is "pseudomedieval," and can best be described as a sort of ageless fairy-tale land that finds itself occupying a little slice of time roughly analogous to Earth's Western Europe during the late Medieval/early Renaissance period. The technology of the setting has not advanced past this point, and while small and subtle anachronisms can be found in both posted stories and live play, we strive as often as possible to rein in large breaches of this guideline, as we feel they detract from the overall feel of the material we've all worked to create.
To whit, there are a few major guidelines in play within the setting:
1) Man-made explosive combustion, outside of that caused by magic, is virtually impossible. Fires light and combustibles do burn, but never violently so, and even steam never seems to build enough pressure to drive an engine or a turbine. It should be noted that guns in particular have no effect in Lyran Tal, as gunpowder does little more than fizzle a bit when exposed to flame.
2) While metal still conducts electricity, nothing (short of a lightning strike or the will of a magician) can generate or store it. This means no batteries, no generators (even if they're powered by the wind or water), and nothing that needs to be plugged in or runs off of batteries.
3) Lyran Tal is a world of craftsmen, and very little is mass-produced for large-scale consumption. Though there is tobacco ("pipe leaf"), there are no machine-rolled cigarettes. Food is preserved through salt and smoke, but never canned (sorry, no Spam here!). Medicines are dispensed through healers or alchemists, using gathered or garden-grown ingredients, and there are no pharmaceuticals in the setting. Beer doesn't come in bottles, and alcohol in general is a "hand-crafted" affair.
Our major point is this: Use common sense, and do your best to steer away from anything that might seem anachronistic or out-of-place for most of the Fantasy novels you'd find on your bookstore shelves. Your character might smoke hand-rolled cigars made from pipe leaf, but he wouldn't have a lighter to light them. She might enjoy a particular type of wine, but it wouldn't be the sort she could simply pop over to the grocery store to get in a cardboard box.
We could explore dozens of other scenarios or possibilities, but if you think "Fantasy" (and feel free to ask one of the locals when in doubt), you should be just fine!