The Dark Mod takes place in a steampunk universe. For more information on Steampunk:
For the purposes of TDM, steampunk means that steam power has been discovered much earlier than in our own history. It allows devices that would normally be anachronistic for a late medieval society.
Many things that seem to be more advanced technology are possible with the use of magic.
The technology of the TDM setting ranges from late medieval to early Victorian, often side by side. Generally speaking, the more modern the technology, the more expensive it is and the less likely it is to be in common use (which is why things like large-scale rail systems do not exist).
Steam technology has been around for some time, and there are many steam-powered inventions in use. Paddle-boats running on steam engines cruise up and down the river alongside traditional sailing ships. Houses of the wealthy are heated with steam boilers and steam-powered generators. Just about everything with moving parts in the city is powered by steam.
Coal is the primary source of fuel for larger steam generators, and most larger houses and mansions will have a 'coal room' in the basement where fuel is kept.
Clockwork machines are also fairly common...large clocktowers and grandfather clocks are expensive, but not unusual. Smaller clockwork devices, like pocketwatches, are rarer and more expensive. The children of aristocrats or wealthy merchants often play with clockwork toys and wind-up automatons.
Gas and oil lamps are the most common form of lighting in the city. Torches are used in poorer areas of town, or in places where people don't go very often, like basements or the sewers. Only the wealthy can afford electric lights, and they must have a generator nearby to function. Magical lights are not uncommon, as the Mages of the Hermetic Order often give them as gifts to the city or to powerful aristocrats.
Magical lights require no fuel to function, and can burn for months or even years without going out. Most cannot be extinguished, though some forms of magical fire can be doused with water arrows.
Since lights are generally expensive, most poorer people go to bed when the sun sets. It is a sign of great extravagance and wealth to be able to host late-night dinners and parties, and wealthy aristocrats often don't go to bed until very early in the morning.
Electricity does not use wires to travel in The Dark Mod setting, but is instead transmitted like radio waves, from generators to the object using the electricity (similar in theory to Tesla's notion of wireless energy transmission). That's why most electrical devices have metal antennaes on them. Generators cannot 'send' electricity very far, so each house requires its own steam-powered generator, meaning only the very wealthy have access to electricity. Electricity is fairly underused in this society so far.
Keep in mind that using electricity to power lights and other objects is a fairly recent development. Only the newest and most wealthy households will have been built with electricity in mind. Most older mansions will have electrical devices (if they exist) built over and around existing architecture in a somewhat haphazard manner.
While explosive powder exists, handheld guns have never taken off as a weapon in TDM society. Foreign mercenaries occasionally carry flintlock weapons, but liquid fire, gas arrows and steam-powered siege equipment continue to satisfy the city's military needs.
The more modern the technology is, the more effort should be put into making it look 'old fashioned'. While the steambeasts of the Inventor's Guild are clearly sophisticated robots, making them appear to be made of old fashioned gears, boilers and clockwork machinery allows them to fit into the steampunk setting. A robot that *looked* sophisticated--highly polished, no obvious working parts--would not. A normal gage might look too modern, but if it used an old-fashioned clock-hand for a needle and roman numerals, suddenly it seems to fit the setting.
For some examples of making modern technology look like steampunk, see here:
Here are some general tips:
Avoid modern looking buttons or small modern light-switches, but instead try hand levers or hanging ropes that turn things on and off. Small wind-up keys or hand cranks are also appropriate.
Rather than large sheets of crystal-clear glass, use small pieces of glass held together by wires. Make the glass cloudy, murky, or otherwise imperfect.
Add prominent metal spikes (antenna). Make the object larger than it might otherwise be, to hold the mysterious working parts inside. Using brass for important metal parts is effective. Avoid blinking, coloured lights.