Lightning Train Design Diary 4: Solo and 2-Player Mode

August 20, 2025

Full steam ahead! Lightning Train, the new bag-building strategy game from designer Paul Dennen (Dune: Imperium, Clank!) has pulled into Friendly Local Game Stores across the US and is now available for purchase, both on retail shelves and the Dire Wolf store!

At last, we arrive at the Lightning Train final Design Diary! Previously, we’ve looked at some of the core fundamentals of the game — such as bag-building and constructing rail lines to deliver goods — and how those elements coalesce into a unique strategic experience, where using your opponents’ rail lines can be just as important as using your own!

In this final Design Diary for Lightning Train, I want to cover what went into supporting modes for lower player counts: solo mode and 2-player mode. Don’t forget to check out our introduction article if you need a refresher on the basic concepts of the game, and you can also check out the full rulebook online!

Solo Mode

Solo was a challenging mode to design! First, we didn’t want to publish a “beat your high score” mode. Similar to the “Rivals” in Dune: Imperium, I wanted a solo player to have the experience of rival companies building on the map, and with interactive decisions, the player would have to find ways to “defeat” them. It was clear from the beginning that rivals should not bag-build, because that would be far too laborious to manage. So rivals would have to play using different rules in order to make this mode work, but with the output of those rules similar to the player’s output.

The core mechanics of the game – building rail networks and making deliveries – give players a ton of agency and possibilities in how they want to pursue victory. Coming up with rules for a rival to pursue such a rich possibility space was a challenge.

Solo Mode: First Concept

The first version of the rules that rivals would follow was card-based, with priority-based heuristics for the bot to build based on that region. At first, I tried simple priority rules, but quickly found that the rivals would build too unproductively and without any apparent hints of a winning strategy. To solve these issues, I added more detail to the prioritized heuristics so that rivals would build more effectively, simulating more intelligence. Ultimately, it seemed like this was going to end up being too complex for players to manage.

This process ended up looking something like this (leaving out the gory details):

Flip a Region Card: The rival will build a rail line in this region, if possible (if it has a station or rail line to connect to in that region). Choose the best rail line to build from the following priorities:
- First Priority: <look for a connection that will connect two separated rail networks>
- Second Priority: <look for a connection that hooks up a production city with resources>
- Third Priority: <look for a connection that hooks up a station that’s not part of a rail network>
- Fourth Priority: <look for a connection that hooks up a production city or, as final fallback, a city with no station>

Yep, it was too complicated! Sure, with this method, rivals ended up building rail lines in a more reasonable fashion, but the process of going through those steps looking for where they would build was brain-draining and not fun. So, I abandoned that method after watching players struggle with it in solo playtests, and went back to the drawing board.

From Cards to Dice

After taking a break from the project to let my brain simmer on the problem, I returned with a new idea: a dice-based method! Sounds a bit random, I know, but the secret sauce of this method was to mark cities on the map with numbers in such a way that rivals tended to build in more reasonable ways. Each city was associated with a varying set of small dice icons to help manipulate probabilities that lead toward better networks.

This obviously required a new map, so the back of the 3-4 player board is used for games with one and two players. Let me explain with an example.

Die results determine where rivals build railways. In this instance, the rival started in Charleston, and built a rail line to Raleigh. This is because a <2> was rolled, signifying the rival to build a rail line to an adjacent city with a matching <2> icon. The rival token then moves to Raleigh, and on their next turn, could potentially build out to Baltimore, Louisville, or Atlanta, depending on the roll.

In solo mode, one of the rivals always starts with a builder token at Charleston (and if Charleston isn’t set up with a neutral station, the rival builds a station there). Whenever a rival attempts to build a rail line, you roll the 6-sided die, then you look at cities across unbuilt paths from their builder token. If you find a city that has a die icon matching your roll, the builder builds that rail line. So, in this case, let’s say you rolled a <2>. There is a <2> on Raleigh, so the rival builds a rail line from Charleston to Raleigh, always taking chips directly from its supply and always including one locomotive while it still has some in its supply). Then, you move the rival’s builder token to Raleigh. Now, for its next build, there are 4 possibilities:

On a <1>, it will build a rail line to Louisville.
On a <2>, it will build a rail line to Baltimore.
On <4>, <5>, or <6>, it will build a rail line to Atlanta.

On a <3>, because there are no nearby cities with a <3>, there is a “reset” rule where the builder will instantly move to the city on the map with the large <3> die icon, which is Houston, and then build out from there.

Sometimes, there’s not a city to connect to matching the roll of the die. In these cases, the rival moves to a different region on the board featuring the same number. Here, we see the rival token has reset their token to Houston after rolling a <3>, and then continues their turn as normal, building a railway to an adjacent city with a <3> icon — in this case, New Orleans.

The rival’s builder resets were an important part of this mode. By placing six reset cities across the board in important locations (Seattle, Salt Lake City, Houston, Kansas City, Detroit, and New York City) and supplementing those “hubs” with carefully-curated dice icons on the cities in between them, this allows the rivals to trend toward building useful rail networks and eventually connecting the Transcontinental Railroad to trigger the end of the game.

There are, of course, more details such as deliveries and building stations. But those issues felt like small potatoes compared to solving how to make rivals build effective rail networks without a lot of contextual logic and rules to process for the player. The dice method was thus the most important breakthrough in making solo mode a fun and playable experience for playtesters. I should also note that there are four difficulty options to support players of varying skill levels, and to let you ascend the difficulties with repeat plays. Try going from lowly Passenger to Tycoon at the top!

2-Player Mode

For 2-player mode (again similar to the philosophy used in Dune: Imperium), I borrowed the rival builder token and dice-based building rule so that a neutral rival could build rail lines during the game. Unlike solo mode, this rival isn’t “in it to win it.” — it is simply there to build rail lines that offer both players opportunities to leverage in their build and delivery decisions. It’s lightweight enough that it doesn’t take a lot of time to manage, but the additional rail lines help make things more interesting for two players duking it out — considering that shared incentives, utilizing other player’s tracks, and building toward the Transcontinental Railroad are a significant part of the game.

With that, I’m going to sign off from the Lightning Train design diaries. I hope you enjoy the game, whether you’re a solo player or not. See you around, I’ve got a train to catch!

Lightning Train is Available!

It’s been fun seeing the excitement for Lightning Train grow since our original announcement. If you’ve been following along, thank you! Lightning Train is now available at Friendly Local Game Stores, and the Dire Wolf web store. Be sure to secure your copy today!

Learn More About Lightning Train: