Let Them Trade

Its a great game - if you know what you can expect or will get.
What you will get: A very relaxed, laid-back, and somewhat easy game. You have a board-game type map. Found your citys, create production chains and buildings, connect them via trade routes. Thats basically it. Just, relax and observe how everything unfolds, how the merchants do their job, how the trade flourish.
What you will NOT get: A challenge, a deep and complex simulation, a fascination story, difficult enemies, or whatever.
Sounds boring for you? Than its not your game. For me, after a long and exhausting day of work - just building some cities, watching how your little wood-empire prosper, without challenges, without action or "save the world"-scenarios is just exactly what is sometimes needed.
However, it took me about 6 hours for the full campaign, so decide yourself if 18$/€ is reasonable for you.

A Promising City Builder with Unique Trade Idea
I played the demo and full game for about 6 hours—almost completed it. The trade-focused economy is a fresh idea and makes earning money more strategic than in many other games. The detailed art and unique level designs are also a highlight.
However, the pricing system needs serious work. For example, tools sell for less than the materials needed to make them, making production unprofitable. Auto-trade struggles to balance prices. Maps are fixed (not procedural), only 4 cities can be built at the beginning, the tech tree is very basic, and traders are too slow—especially across long distances. Faster transport like trains or planes would be great in the future.
In short: a great concept, but the core trade and economy systems need a major redesign.

Ignore the negative reviews. This is literally described as a cozy economy builder - and that's exactly what it is. Little campaign to get you up to speed with the game, and then some inbuilt maps to refine your techniques. Plenty of opportunity for further updates, and a growing amount of custom maps on the Workshop.
This is a cheap game, and you'll definitely get your money out of it!

Summary:
Excellent Game. A small city builder / economic simulation with a board game feel.

Graphics: Cute - wooden toy style.

Mechanics:
Interesting if you are into production chain games. The mechanics (incl the self adjusting market prices) are deeper than it appears at first glance.

There is a bit of a puzzle element here as you have limited number of towns each of which having limited slots for production buildings.

There is a minimalist combat element where you defend against NPC thieves that can intercept your traders and steal your goods. But this is more of an annoyance and adds little to the gameplay. Probably meant to keep you busy while you are waiting for some required resources to accumulate.

Replayability:
Medium. After the campaign/tutorial (which is well done) you can play on several different maps in a sandbox mode. The winter update introduces a slightly more challenging map. User created maps can also be downloaded.

Variety comes from the fact that you need to adjust your town layouts (i.e. which production buildings go into the limited slots of each town) based on the resource distribution available, Since each map needs to be explored first you don't have upfront knowledge of the resource locations when you start planning which adds more challenge.

However - in sandbox mode your goal is always to get to the highest tier of citizens and then run the "party tent" successfully (Have lots of high end goods) . So that is a bit repetitive after a while.

Price: I feel fair for the amount of content provided. Good for 30-50 hrs. Then you have seen it.

Okay, okay, get this: They trade, and you let them.
In short, it's a casual strategy game with all of the pieces present. Since the best way to combat low potato prices is to cause a brief tiny little famine, it's even got the Geneva Checklist aspect of any good strategy game covered!
Why I'd pick this up:
The game succeeds at its goal of turning the traditional production model on its head. Underproduction is bad, but low tax revenue is worse!
It's calm and slow-paced with no real way to lose, but includes speedup to combat waiting times.
The art style is cute and consistently executed.
Why I may wait for a sale:
Game's not awfully long, though I think any longer would overstay its welcome. You'll have your 12-20 hours of fun.
The campaign makes you redo most of the tech tree in each mission. I like redoing the setup because each map is different and you'll have a better forward plan with experience, but having to build a grain farm, wait for enough grain to research a mill, build it, then wait for enough flour to research a bakery, and finally build that gets a little grating when most intermediate products have little to no use outside of their production chain.
There are some rough edges. The city AI feels a bit dumb or outright broken sometimes, refusing to tend to basic needs when we vastly overproduce fish, for instance. Multiple times, bandits popped into existence IN FRONT OF MY CASTLE. You'd think we would've seen them! Certain modifications (Lumberjack Guild, potato farm shared fields) are not correctly reflected in the production graphs.

I would tentatively recommend this assuming you know what you're in for.
Let Them Trade is a fairly simple and chill logistics based city builder where you construct and upgrade cities with associated production tiles. Each city can produce its own goods and cities can be interlinked with roads to allow for trade between them to collectively meet the needs of the people in all the cities. Efficient city planning paired with a research tree allows you to accumulate wealth and see the cities prosper.
I found the core experience of the game quite enjoyable, it's a fairly relaxing and low stakes game which you can complete within several hours as it does not take long to complete the research tree and max out all your cities. The visuals are simple but nice to look at, the music is pleasant and the game-play is pretty straightforward. I think it serves as a good game to play whilst you do something in the background like listen to a podcast etc.
I would however say, the game is fairly basic in its current state, perhaps too basic. The technology tree is very brief and feels a tad unfinished, like it should have more options but it doesn't. The game also has a bandit system where trade routes can be attacked but that whole aspect is more annoying than anything else (you can thankfully turn it off entirely). Throughout the game I do keep getting the feeling of wanting more, more resources, more cities, more technologies. Whilst the core game is fine, I feel like the line between relaxing and boring is very fine and Let Them Trade is teetering on the edge.
I think to improve the game moving forward, the devs should add more meat to the bones here, I don't think added complexity will take away from the laid back vibe the game is going for. I think some design decisions need refining as well, I think the individual perks of production tiles you can select are tedious to manage. There should just be a separate page where you can control the global selection of perks for a specific production tile type instead of clicking on them separately, something like a branching upgrade tree where you choose to specialise the tiles for specific purpose. I also think knights should have a patrol option seeing as you can only have 3 at the most and the range of guarding they provide is minuscule compared to the map size. Having them patrol the roads of a certain area seems far more sensical than constantly moving them around.
All that being said, if you go into the game expecting a simple, chill albeit brief city building/logistics experience, you will get that. However, if you're looking for something more involved that you can play for a longer amount of time with added complexity, probably look elsewhere.

Fun game but campaign is a little short and free play is not interesting enough to play for verry long