Regner's OEG 102 Tram "Paul" became my first live steam loco. I met the original in a museum when I was a schoolboy, hence I could not resist.
I do 1 gauge, but tram locos tend to be tiny even in narrow gauge. She fits nicely in length and width, if a bit tall compared to Maxi coaches. I think she will do freight duty with lowsided wagons next to her where this won't show.
Technically it is an oscillating steam motor drive with clockwork gears.
Note the whistle on the opposite end. I added wooden beams to that buffers would not scratch the fronts.
The roof lifts for cab access. From front to back you have the steam motor and its reverser lever, stack, safety valve and pressure gauge. Note the baffle I put in to protect the steam engine's spring from the smokebox. When I had a false start trying to ignite the gas, flames there destroyed the spring that holds the cylnders. Moving to the backhead, there is the steam manifold supplying steam valve, pressure gauge, whistle and sightglass with water refill valve on top. Ultimate left you can see gas valve and filler with tank below. Opposite right you can make out the shiny lubricator cap.
Besides the cab fire mentioned, which was entirely my fault (Bring the light first, then turn on gas! that's what I learned.), she turned out to be an uncomplicated, reliable and comfortly slow paced runner.
Thus encouraged I bought another loco, this time a used Else. This forum does have an Else thread already to which I may add in due time.