Disclaimer: I received a free copy of this product for the purpose of this review.
Babbage's Engine is a 28-page, full-color adventure for the Castle Falkenstein system with a generous helping of art sprinkled throughout. After a brief introduction to the main NPCs - there aren't many, so they'll be easy enough to keep track of - this product jumps right into the meat of the adventure. To avoid spoilers, I won't be describing the plot in too much detail - the description above should suffice for that.
The adventure itself is broken up into four chapters and an epilogue, most no more than a few pages at most. It's entirely playable as a standalone adventure, but the story is such that it's also a pretty good chance to set up future plot threads and introduce NPCs the players might meet in other games. Some advice on doing this is provided, along with several notable figures (Jules Verne, Mark Twain, etc.) who might be aboard.
Following the adventure, Babbage's Engine offers six sample Dramatic Characters appropriate for the adventure, complete with print-ready character sheets that can be passed around. These aren't enough to play all by themselves - players will need to be familiar with the Castle Falkenstein system to make sense of the sheets - but they're pretty handy for groups that would like to jump right in.
Overall, this is a very solid release, and I feel like it accomplishes exactly what it set out to do - provide a train-based dramatic adventure. It's probably best for linking other adventures together - I mean, literally, you're riding from one destination to the other, but it'd definitely be more fun than simply saying "now you're on the other side". The price is very attractive for the amount of content you're getting, too, especially because this is probably a full session's worth of material (unless you have very long gaming sessions). I'd definitely suggest trying to finish it in one sitting, though.
Overall, I feel like this product is about a 4.5/5 - maybe not quite perfect, but quite solidly put together, and certainly not something I'd hesitate to suggest Hosts take a look at. For the purposes of this platform, I'm rounding up.