Deep Dive: Creating an asynchronous multiplayer in Solium Infernum

Game Developer Deep Dives are an ongoing series with the goal of shedding light on specific design, art, or technical features within a video game in order to show how seemingly simple, fundamental design decisions aren’t really that simple at all.

Earlier installments cover topics such as how Mimimi games crafted the save scum-friendly save system in Shadow Gambit: The Cursed Crew, and the technical work and creative nuances behind Slime Rancher 2's new weather system and the experiential impact that developers Monomi Park designed for players, and the marketing strategy that helped Timberborn's popularity soar with only two years in early access with Mechanistry comms manager Michal Amielanczyk.

In this edition, principal designer Anthony Sweet tells us how below-the-waist gameplay enabled by above-the-table machinations helped create a complex asynchronous multiplayer in Solium Infernum.

Hello! I'm Anthony Sweet, the principal designer on Solium Infernum at League of Geeks. Today I'll be talking to you about our take on asynchronous multiplayer, and how we've designed the dynamics of Solium Infernum to foster its unique sense of scheming inside and outside of the game.

But where in Hell?

There’s a scene very early in John Milton’s Paradise Lost that describes the landscape of Hell in which the recently banished Satan and his fallen angels find themselves;

There were many different locations Milton could have picked for this opening scene, and it’s an interesting storytelling decision that he chose this location. Satan finds himself at his absolute lowest, having miscalculated his potential to overthrow Heaven, and has been cast into this dismal place where even great furnaces fail to light the darkness. Opening at this point in the story, in this location, fosters sympathy for someone who we shouldn’t feel much sympathy for at all.

Writers make conscious decisions about where their scenes take place because it has a dramatic effect on how the story plays out. During the development of Solium Infernum, this was a question I often brought up with our design team: where does this game take place?

The obvious answer is Hell, of course. But the question wasn’t intended as a narrative design discourse on the game's setting. Instead, I was asking for the team to consider: where do players play a game of Solium Infernum?

Because the answer isn’t as simple as “on their computer.”

Bringing Hell home

A quick history lesson: Solium Infernum is a Hell-themed turn-based strategy game, originally released in 2009 by Vic Davis and reimagined by League of Geeks in 2024. The premise is that Satan has disappeared, leaving the Infernal Throne vacant, and players take on the role of an Archfiend intent on bending the laws of Hell’s bureaucracy as they vie to rule Hell. Whoever earns the most Prestige points via diplomacy, skulduggery, and unadulterated ambition by the end of the match takes the Throne and is crowned the new Dark Majesty.

No one said the path to victory in Hell would be easy. Every Archfiend waits for their opportunity to manipulate, extort, lie and fight you. Image via League of Geeks.

As a strategy game, Solium Infernum invokes a feeling of paranoia-fueled political manipulation and focuses heavily on the diplomatic resolution of conflict between players. Wars cannot be started until a player has the correct political justification for the invasion, typically by forcing their opponent into a bad decision with strategically timed demands and insults. The game can be played single-player against AI or asynchronously with other players, often at a rate of several turns per day, resulting in matches that last weeks (if not months).

When I first joined the Solium Infernum team at League of Geeks in 2022, I got myself a copy of Vic’s original game and played it for the whole weekend before my first day on the job. It very quickly became clear to me that the strategy game I had just played for 20+ hours against rudimentary AI would be a vastly more terrifying political playground when facing human opponents.

Sure, the AI opponents were sending demands and lining up their armies along my borders, but against human players, I could already see the social and political manipulations that were possible. Alliances and backstabs, kingmaking rug-pulls, and social manipulation… as an avid fan of traitor mechanics in board games, I couldn’t wait to get my hands on these systems.

During my first multiplayer game, I realized that my expectations didn’t even scratch the surface of what was possible in a game of Solium Infernum, especially against five other players. I lay awake at night, plotting the downfall of my nemeses. I schemed in my sleep. I missed keynote presentations at a prominent conference because I was holed up in my hotel room, trying to figure out how to snatch victory in a war I probably shouldn’t have started, except that I was goaded by my hubris because of an in-game message someone had sent me earlier in the week.

Solium Infernum was a game that was installed on my computer, but I played it every waking moment in my mind’s eye.

Above-The-Table play

When I joined the design team at League of Geeks, I wanted to make sure I conveyed clearly where we play the game. The gameplay vision for Solium Infernum is an experience in which social manipulation should be just as powerful as mechanical mastery.

Players will make complicated mechanical decisions (and Solium is a mechanically dense game!), but those player decisions will often be dictated by social and political pressures from other Archfiends. A player can be presented at any time with a mechanically dominant choice, but due to the social history of their game, they may instead choose to avoid, downplay, or subvert that action.

In this above scenario, Belial (blue) could continue to prosecute his war against Beelzebub (green) for easy Prestige, but he also knows that Erzsebet (pink) would like to attack Beelzebub’s Stronghold and remove them from the match entirely. Erzsebet has the means to pass through Belial’s territory with his permission, so Belial has a decision to make; allow Erzsebet to eliminate Beelzebub, or continue to bully the Beelzebub for Prestige but risk angering Erzsebet who sits right on his border. Image via League of Geeks.

We break down the gameplay of Solium into two categories: on-the-table gameplay is the combination of systems and dynamics that the player directly interacts with, and above-the-table gameplay is the social play space of politicking, bluffing, and misdirection. In a game that is about being dastardly manipulative and Machiavellian, we have to ensure that players are given the opportunity and possibility space to engage meaningfully in this political ecosystem.

This distinction of above-table gameplay has filtered through to numerous design decisions made throughout the game’s development. Decisions such as which rituals are resolved publicly versus privately, how much information we give when someone purchases a powerful artifact, and even how we communicate each player’s win conditions are all processed through the design lens of "how do we encourage more politicking between the players?"

By clearly adding the possibility space of above-the-table gameplay to our design process, we made sure we didn't forget the fundamental gameplay vision for Solium Infernum. We knew that players would spend time outside of the game thinking about their next moves. We had to make sure there were enough gameplay hooks and information asymmetry to keep their Machiavellian player fantasy scheming even when they weren't in the game.

The Friendship Destruction Simulator

The multiple domains of strategic gameplay meant that we required design solutions we otherwise would not have needed for a more mechanically straightforward game.

One of the key systems that fuels the deception and bluffing that occurs between turns is our Knowledge system. At any given time, the game has an accurate snapshot of how much intelligence you have actively gained about your opponents and will provide you with the correct amount of information about their military forces, their economic power, and their personal stats.

A player can improve their level of knowledge by investing in their Prophecy power, which gives access to the Dark Augury ritual and unveils the secrets of their opponents. Dark Augury makes information distribution intentionally asymmetrical. Just like in the original Solium Infernum, Dark Augury is incredibly valuable for high-level play, so it’s no surprise that Prophecy players often become brokers of other people’s secrets. This creates a very interesting social dynamic among the players of a match.

Dark Augury provides opportunities for players to learn more about their opponents. What they choose to do with that information afterwards is up to them. Image via League of Geeks.

A common example we see is the purchase of Praetors. These are military champions who are often publicly attached to Legions and paraded around the map. However, a Praetor can also be used to challenge other players to duels to the death for high-stakes Prestige gambles. If you find yourself with a Praetor in the early game, and you know, through the power of Prophecy, which players don’t yet own one, you can net yourself a significant Prestige advantage by challenging them to duels that they can’t comply with.

Looking at this dynamic through the lens of above-table gameplay, we chose to continue the original Solium Infernum’s decision of keeping non-Legion purchases anonymous. When a Praetor, Artifact or Manuscript is purchased, every player will receive a turn log message that alerts them to has been bought, but not by whom.

Unlike the original, we allow the player to unlock that buyer information in the Prophecy skill set. Now as a competent Prophecy player, you will find out who has purchased the dueling specialist Praetor, or the game-changing Devourer Statuettes artifact, without either of them ever needing to reach the board. This asymmetrical release of information creates a social dynamic that encourages players to discuss, barter, and bluff amongst each other to find their edge over everyone else.

It’s a very specific Solium Infernum feeling to set up a convoluted political trap for your friend and watch over multiple excruciating days as your intricate mousetrap catches its squirming prey. Hopefully, with time, they will still be your friend afterward.

Evil scheming anywhere, anytime

The time scale of a multiplayer Solium Infernum match means players can have a long time between turns to think about their plans, which is great for accommodating many different levels of multiplayer commitment. Even in single-player, it's not uncommon to hear of players spending up to an hour considering their options before they submit their turn. These dynamics result in a lot of gameplay happening inside of the player's mind, not necessarily in the game itself. It was important that Solium Infernum was designed to be easy to return to so that you know exactly where you left off in your scheming.

Your messages with your fellow Archfiends have a viewable history, so you can go back and review your plans with your temporary ally from twenty turns ago, but we also allow you to behead the messenger, which mutes any player you no longer wish to hear from. Multiplayer games can be played live in our Sessional mode for a digital simulation of board game night, but we also implemented localized Steam Turn Notifications and a match-specific Notepad to help with the one-turn-a-day asynchronous games that stretch out over months.

Ultimately, the core of every design decision we made for Solium Infernum came down to answering that initial question: where is the player going to play this game? For me, it was at 2 AM staring at the hotel ceiling, piecing together a plan to finish a war with my one fragile Legion still in one piece. For the rest of our players, it’s going to be in all manner of permutations of life circumstances.

Asking this question meant we created design solutions not just for different strategic playstyles but also different social dynamics and engagement rates. This has made Solium Infernum a strategy game that I am always playing, even when I’m not at my PC.