Nice, hands off recirculating steam engine. Quick start-up, creature comforts, and nice and zippy! Seemed particularly relevant since I'm preparing for a Deadlands game.
I'm waiting for the Cyclone steam engine to FINALLY drop for consumer use, which I suspect is going to take off in a big way because power-to-weight ratio, fuel flexibility, ease of use, and price. Direct drive, no coolant system, no oil (water lubricated), no exhaust stuff (still has exhaust, but needs no muffler or emissions things) means it's basically going to be a perfect drop in engine for people looking to create stuff without much knowledge of things like gear ratios. But that will get its own post when they finally DO SOMETHING with the damned thing worth reporting, aside from occasional reports that someone else has partnered with them.