Mini Metro

I’ve been waiting over 3 years for this game to come to iOS, I kid you not. To understand why, you might want some backstory.

So it was my senior year of college and I was spending my final term abroad in Italy. We had just spent the day in Perugia, an old town known for its chocolate and manufacturing. But the thing I was rapidly falling in love with in Italy was the transportation system. In part because it was so different, but in part because it was such a freeing combination of train travel and walking that felt like such a different experience from the walled-in american travel adventure.

And Perugia had built a service called the Mini Metro (not joking, it had the same name), which is basically a subway system in miniature, taking people from the surrounding areas in the valley on a one way trip up into Perugia proper. It looked like a wildly expensive project built for a European architecture/cultural extragavanza in 2019. Of course as a tourist I fell wildly in love with it. This was literally the same day that I was introduced to the game Mini Metro.

Mini Metro, the game, if you’ve never heard about it, is a (seemingly) procedurally generated city-planning game where players are responsible for connecting stations of different shapes. Travellers will pop up in these stations and be required to be transported (via the metro) to the corresponding shape. For example a square traveller might appear in a circular station. That traveller will have to get to a square station before they get off. As the system grows, strains will appear that challenge the player to keep it running smoothly. The game ends when a station overcrowds.

I first encountered the game as a unity based browser game. The initial implementation was much more sparse than the iOS version. It was simply a map with a single river running through it. Stations would appear on the map over time, and the size and complexity of your system would grow. The game would ultimately spawn a release on Steam, however I (personally) wasn’t very interested in that.

The game on Steam, similarly to the game on iOS, included additional levels, and a couple of new tweaks to the game which make it sufficiently diverse that it’s fairly easy to find something you haven’t done in a while and play it for fun. However, I wasn’t that interested (as a player) because I felt the interaction was really suited for a touchscreen.

The Mechanics

So let’s break down what’s going on:

The game starts with three stations *(take photo)*, a square, a triangle, and a circle. The player will have a limited number of lines (always three to start) that they may use to connect the shapes to one another. The lines are represented by different colors.

1. The main player action in the game is dragging connections between stations, marked as different symbols on the screen.

Once the line is drawn, a small rectangle will begin moving between the station, picking up passengers, and dropping them off. The action itself is simple enough to be very addictive. It doesn’t ask a lot of me as a player. All I have to do is figure out what nodes to drag between and then I get to see the rest come to life in front of me.

Playing this game on a computer was a different experience. It’s similar to the difference between selecting a word in a word processor using a mouse v. using a touch screen. It’s possible in both situations, but using a mouse is much more precise. Similarly, the disconnect between the mouse and the pointer actually made placing lines more difficult and less efficient, because a dragging motion on a mouse isn’t as natural. Secondly, from my personal perspective as a player, the act of sitting down to play a game is a commitment of time that I have certain expectations for how the game’s experience is going to unfold that Mini Metro didn’t match.

1a) However the rectangles (the cars), have limited space. They can only carry 6 passengers at a time, and will only pick up passengers if they can successfully deliver them to the next position. This is where the tension and the fun of the game come in.

2. The decision making process is also straightforward. As a player you have two things to pay attention to:
1. Which lines are going to connect new stations.
2. Preventing existing stations from getting overcrowded.

And this is what the game does really cleverly. The majority of what actually happens is passive. The city will continue chugging along quite happily (for a while) without any of the player’s interactions. It’s the player’s role to address and foresee what’s going to happen, to make sure the growth continues in an optimal fashion.

From a mechanical perspective, the game has two branching mechanisms, one soft one hard.

Soft Branching

A soft branching system means a player can make reversible decisions, but at a cost. The most basic version of this is an economic system based on trading currency for goods. Goods can be sold back or traded later but at a transaction cost.

The main decisions players make in the game is determining which train lines will connect the different stations. The players can later pick up the lines and move them to different places, but at the cost of having to wait for the trains to complete their usual route.

This creates an interesting tension. Players feel comfortable making decisions because of the relatively small opportunity cost, but as they add up it gets harder to change them over time.

On the one hand, drawing a line to a single station is a low opportunity cost. I can pretty easily change it at any time. However, as more stations go up, and more trains are committed, it becomes harder to change the placement, not because of additional rules, but because the game state has grown to a state of complexity that naturally makes it difficult. I can’t overemphasize how challenging a state this is to make, because it feels natural. As a human we’re comfortable with situations where there are natural ramifications for our choices. It’s harder to grok situations where the rules tell us we can’t do something. We always end up asking, *”but why?”*.

However, there are also hard branching system in the game.

Hard Branching

A hard branching system is one in which a decision cannot be taken back, exchanged, or reversed. The best example of a hard branching system is a skill tree in an RPG. Most skill trees cannot be exchanged or reversed. They open up new opportunities but they also restrict future opportunities.

Mini metro offers hard branching decisions in the form of “expansions”. Every week as the city grows the player is offered a new choice. The most common choices are between an additional line ( to more easily connect cities), tunnels (to take a line across water), or a carriage (adding additional capacity to existing trains).

What’s especially exciting about the hard branching system is the natural breaks and pauses the game gives you when you make these irreversible decisions. There will be points where you just hope to get to Sunday (the end of the week when you get your next boost), so you can get that additional train or station upgrade to alleviate some pressure from your overcrowding stations.

However you only get to choose between one of two options. Even though there are around 3-5 options that the game *could* give you, on any given week you only get two. This serves two crucial purposes.
1. It limits your choices so you aren’t paralyzed. Usually there is a clear short term option you can choose. This makes your life easier. If you want the easy pick, just take it and move on. If you could choose between any, it would _feel_ like a huge calculation just to figure out what goes where.
2. Sometimes you just get unlucky. Sometimes you’re counting on an extra line or an extra carriage to target a very specific area, and you just don’t get it. That uncertainty builds in tension and excitement that wouldn’t be present otherwise. It also means play situations will change with every restart. As a player you mostly have control over how things will go, but the ways you don’t have control can make a huge difference.

3. Non-intuitive pattern matching.

Pattern matching as a mechanic is a staple of games and especially phone games. It is an easy goal to grok as a player and it is catchy in that the attempt reward cycle and be repeated many times in succession for the player.

The twist that Mini Metro adds is that you the player can wholly accept or ignore the pattern matching element as they want. You could play an entire game of mini metro while completely ignoring pattern requirements and have a very pleasurable experience just watching the trains go back and forth, and the “passengers” appear and disappear from the stations.

However, a more experienced player can look at the relationships between stations, based on location, and find the most efficient route between two stations, that will ultimately keep the trains running longer. This is what Mark Rosewater has called linticular design, when a mechanic is simple enough to be appreciated by people who are taking the game at face value, and nuanced enough to be strategized on top of.

It is very hard to feel bad playing the game. There are a relatively small number of decisions, the pace of the game is smooth and slow (with a peaceful soundtrack).


The reason I was *so excited* about the game coming to iOS (iPad and iPhone) is that the specific game actions felt uniquely suited to hand gesture. On a screen (where the game debuted) you mainly focus on click and drag actions, while tap and hold is much more natural.

One of the other challenges the game faces on iOS, however, is how to communicate to players what they are tapping and dragging, where it is going, and when it has gotten there. When the user drags a line on or off a station a colored pulse will emit from the station to let you know that an action as occurred. In addition, little T shapes poke out of the stations where the player can easily grab hold of to move or extend the line.

The game also does a great job of expanding as the stations in a line increase. When the game start, the 3 initial dots take up a majority of the space. However, by the time the game ends, the screen has expanded to give the player a full view of the city they have been building. By focusing the player and expanding out slowly it helps focus them on the goals that need to be accomplished, not necessarily where the city might end up. It’s also a great usability point too. There’s no need to add extra information if it’s unnecessary.

(maybe add some shots of where everything is at)

Narrative and Reality

Before I close it’s important to talk about the story of the game and what it means. Often it’s important in a game such as this, that tries to closely mimic reality, that the spots where it diverges (even minutely) can seem out of place:
For example, in a real metro system, there is a very specific ebb and flow to how and when passengers will use the system. Passengers aren’t trying to get to “any square station” but to a very specific station that helps them accomplish their objective. The game, very clearly does not do this.

This is not the look of a realistic metro system.

Secondly, city planners can’t just pick up and put down metro lines whenever they damn well please. (Although it would be pretty freaking sweet if they could)
But is this necessarily a failure?
I would argue it is not a failure, on two counts.
1. A system with a clear flow would be easier to strategize around, and potentially be less fun. There just wouldn’t be as much challenge if it was very clear that on the San Francisco map traffic increased in the morning and the evening, and moved in one direction.
2. From an aesthetic/player perspective, the goal isn’t to recreate a city system, it’s to (peacefully) recreate the experience of dealing with the stresses of an expanding metro system as new stations pop up and more passengers pile on. It accomplishes this, and in doing so supports the larger goal.

Who is the game for?

Every game has a type. What is the context I can imagine playing the game? Play sessions aren’t so short that you can cover it on the toilet or on a commute, but they’re also self-contained, so you can easily put it down, and pick it back up in a few hours without feeling out of place.

Though there is a score that makes the game exciting, the driving point isn’t to rack up a high score, and so the game probably won’t appear to the gamer who likes ascending a scoreboard. It’s a puzzler-civ game where the player gets to continually enjoy the fruits of their labors while also being challenged by some of the twists and turns.

Now to be thoroughly biased

Similar to the adorable mini metro *(must add photo of mini metro in italy)* the game caught my eye for it’s clean aesthetic and unpretentiousness. I personally love playing it to see how the map will grow while it brings back memories of the fun I had in Italy, exploring a new land.

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