There have been a lot of visions of the post-apocalypse, but if you've been waiting for one in which a sleepy-voiced robot guides you through a series train-based environmental puzzles in the year 2525, then you're in luck. Also, you're a little strange. Also, this mod is a little strange, even in name. It's called Steam, Tracks, Trouble & Riddles and it's for Half-Life 2: Episode 2.
First, some back-story, which is presented nicely through a series of hand-drawn images. It seems the Cuban Missile Crisis didn't end so agreeably in this reality. The nukes were launched, humans were essentially wiped out, and... well, frankly, how that leads to solving train puzzles in Berlin in the distant future, I'm not entirely sure. The important thing is, there's a bunch of train puzzles and a friendly robot to help you solve them.
It's notable that Ross Scott voices the robot, which is cool, though his voice has been slowed down to the point where it feels like it could be anyone reading the lines, which is sort of an odd choice. I'm fairly sure Scott didn't write the script, either, as the robot isn't particularly funny. The robot is, however, well designed and animated, and I enjoy the fact that he has another, smaller robot living in his head who pops out now and then. Also, for a robot who trundles around on a single wheel, I find him much more enjoyable than, say, Claptrap, especially in terms of volume.
The first thing you do in the mod is sort of the worst thing: you manipulate the slowest-moving crane ever built into picking up the parts of a railway handcar and drop them into a pile. It's not hard, and there's only three pieces, it just takes a while. If you can power through it, things get more enjoyable.
Once built, you drive your handcar along the tracks, stopping at occasional obstacles. Maybe there's a bridge that's not aligned properly, or a wall that needs to be destroyed, or some other sort of obstruction or obstacle on the track, meaning you'll need to stop, get out, look around, and figure out what the heck you're supposed to do. Often, there's a bit of guesswork involved before you can even start working on the puzzles. A series of valves and pipes means you'll need to open some and close others, obviously, but it can take a while to figure out exactly why the ones that need to be closed need to be closed. Y'know?
Of course there's a generator puzzle, and some batteries have to be fetched to power certain devices, and this being built in Half-Life 2, you'll naturally need to find a cable with a giant plug to plug into a giant plug-hole at some point. There are also some explosive barrels to be disarmed, as well as some electrified tracks and poison muck to avoid falling into. Finally, you'll face a massive gauntlet of moving trains while traversing narrow passages near the end, which is sort of like playing Frogger from a first-person perspective. You can't sprint in this mod (for some reason) but hopping will speed you up. I recommend hopping. I recommend hopping everywhere, in fact.
Help from your robot pal is somewhat intermittent. Sometimes he'll tell you exactly what to do, but other times he'll only provide encouragement. "Good job!" he said at one point, when I had been opening and closing valves more or less at random for several long minutes. It wasn't terribly specific, but at least he'd let me know I'd done something right, which helped me figure out the rest of the puzzle.
This isn't a terribly long mod, maybe two hours, unless you get stuck. (If you do, there's a lovely and fully comprehensive walk-through PDF created by the modder in the download section below). It's a bit uneven: some portions are really beautifully done, especially the robot and some of the custom machinery you'll need to manipulate, while some portions of the levels can feel a bit plain and uninspired. It's also not something to speed through: a lot of time needs to be spent just wandering around the various puzzles, experimenting and trying to determine what needs to be done. If you're looking for a thoughtful, mostly gentle, moderately paced puzzle mod, though, this is a nice one.
Installation: It's easy! Just download it here, open the .rar file, and drop the contents into your /sourcemods folder in your Steam directory. Then restart Steam and you'll see S.T.T.&R. in your Steam library, ready to launch.