Steampunk is cool, of course, but when you're creating your own setting you might feel that steam power alone isn't enough to justify such advanced technology. After all, the historical Industrial Revolution failed to produce airship armadas, Humongous Mecha, or legions of steam-powered war robots.
You could just give it a Hand Wave and say it runs on the Rule of Cool, or you could apply some phlebotinum to it. Whether it's an Alternate Universe of our Earth or a Constructed World the alternatives are plentiful, from rare minerals and other substances to something a bit more magical (in which case Gaslight Fantasy and/or Dungeon Punk possibly overlap to some degree). Either way, Single Phlebotinum Limit is likely to apply.
- Princess Principal takes place in an alternate 19th century Europe where Albion discovered cavorite, an anti-gravity mineral. It fueled a technological revolution in Albion that allowed the nation to build high-technology airships and become a world superpower. Albion itself looks very steampunk, with all the trappings of Victorian London.
- The Steamballs of Steamboy. Not only are three of them able to keep a giant castle floating in the air and provide almost unlimited quantities of steam at high pressure, they remain at room temperature the entire time. This has something to do with a mineral dissolved in the water they're filled with. That's all they say about the matter.
- Undocumented Features: The "Aegis Florea" stories based on Sakura Wars justify the steampunk by moving the setting to a Japanese-settled colony with virtually no resources except coal, iron, and water; the colonists decided to revisit old technology rather than depend on imports, eventually reaching a technology level similar to the source material.
- Red Alert 3 Paradox: The Order of the Talon's steam-powered tech is capable of going toe-to-toe with the Weird Science of the Allies and the Mecha of Japan and coming out on top thanks to the impossibly tough "Talon Steel". With Talon Steel, the Order's steam boilers can be at incredibly high heat and pressure without issue, and the same resilience allow Talon Steel clockwork to be wound to ridiculous levels of Tension. It also doesn't hurt that using it for armor makes their units stupidly tough.
- Anti-Ice by Stephen Baxter is set in a steampunk 19th century based on the discovery of a form of antimatter that can be stored and transported relatively safely.
- 20,000 Leagues Under the Sea: the Nautilus is powered by electricity, then a new and exotic power source. Unfortunately, Verne overestimated what electric power was actually capable of, so the Nautilus as described in the book wouldn't function. Presumably, this is why it runs on nuclear power in the Disney version, since at the time the movie was made, nuclear power was the cool new power source.
- In Blades in the Dark (strongly inspired by the Dishonored series), the industrial revolution was kicked off by the discovery that the blood of the demonic leviathans roaming the Void Sea can be used to produce electric power. By the time the game takes place, its setting is roughly in the Victorian age, with most technology powered by electricity extracted from leviathan blood (although some older tech also uses steam power).
- In Deadlands, the steampunk mechanisms are fueled by a miracle fuel, ghost rock, which is a supernatural mineral made by the Big Bads from damned souls.
- The Jadeclaw 1st edition adventure module "Loot the Burning House" featured a province of Zhongguo rediscovering steam power and examples of ancient steam engines powered by alchemically treated metal octagons instead of wood or coal.
- In Magic: The Gathering, the plane of Kaladesh focuses on an industrial revolution caused by the harvesting of aether (essentially the essence of the cosmos itself, made workable thanks to the multiverse-shaking event known as the Mending). Word of God states that it is the franchise's take on the steampunk genre, with rogue inventors, government oppression, and airships, albeit eschewing the traditional Victorian setting, clunkiness, and grime for a Fantasy Counterpart Culture of India, technology that prides form as much as it does function, and a distinct touch of Solar Punk (thanks to aether being zero emissions and ethically harvestable).
- Downplayed example: a Pyramid magazine article for GURPS Steampunk proposes that GMs who worry about this stuff might like to introduce liquefied coal, as a reasonably plausible efficiency-booster that the real-world Age of Steam never used. For GMs who aren't worried by realism, the Steam-Tech book has exotic "rays" and etheric technology.
- Dishonored takes place in a Constructed World, but it still has an equivalent to Victorian Britain and an industrial revolution to go along with it, in this case, one fueled by the oil of supernaturally attuned whales that exist simultaneously in the mortal world and in the Void. The end result is a setting much like the darker versions of traditional steampunk, flavored with Gaslight Fantasy.
- Ironcast is set in an alternate Victorian Britain anno 1886, where the harvesting of the mineral voltite ( actually a sentient alien lifeform) has led to the development of airships, powerful energy weapons, and the eponymous Ironcasts, as well as a devastating war with France.
- Steambirds: The main premise is that fusion power was discovered in the 19th century, so while the planes run on steam, they don't need coal to function.
- In Widdershins, the titular English town uses steampunk tech imbued with spirits of emotion, like Clockwork Creatures that contain their creator's Pride and steam locomotives with a boost of Impatience to speed them along. While most of the story is set in the Victorian era, the town maintains the technology into the modern day, because the Background Magic Field near Widdershins' magical Anchor is strong enough to disrupt electronics.