AI in solitaire/co-op boardgames: How should it work?

But why not? I already acknowledged that these situations are thematically muddy, because it confuses the question of exactly who or what the player is controlling. But I don’t see them as inherently problematic from a game mechanics design point of view. Do you?

Imagine that Gloomhaven’s ambiguity rule for monster attack targeting was replaced with “At any time as a free action, a hero may bang their weapons together and yell 'hey ugly, come and get me!` Any time a monster is deciding between two equally valid targets for an attack, it targets the hero that has done this most recently.” Same mechanic, conceptualized with different flavoring: Would you still consider this problematic “playing on the AI’s behalf”?

Equivalently, what if a wargame said “The player controls the Allied forces, plus one double-agent German intel officer who subtly sabotages their decision-making process from time to time.”?

A bit clunky conceptually sure, but I don’t see it as an inherently illegitimate way to design game mechanics. And I’d be intrigued to play a game that leaned into this sort of thing and took it even further, and said, for example, that every turn the enemy forces draw three possible action cards that are bad for the player in distinct ways, and the player chooses which one they will execute. Conceptualize it however you like (information warfare, traitor in their midst, bureaucratic incompetence, etc.), but I think there could be some interesting decisions for the player to make there.

In a recent game of Marvel United, on the villain’s turn, the action card says that they move to the nearest hero, attack, and spawn two thugs. Ant-man is two spaces clockwise, and Hulk is two spaces counterclockwise. Do I play it safe and send the villain to Ant-man, who has shrunk and is immune to damage? On the other hand, Hulk would be really hurt, but could retaliate by smashing all thugs at the location which would let us complete a mission. And what’s in the other locations nearby where the villain might move next turn? The right answer is non-obvious and requires thinking through what might happen.

Sure the game could have included exhaustive tiebreaker mechanics here, but in this case it would have robbed me of an interesting decision to make, so I’m not willing to call that a categorically better design.

I guess what I’m getting at is that every game consists of periods where the game mechanics dictate what happens, punctuated by moments where the player can make a decision. In evaluating a game, I want all of those decision points to be characterized by unity of purpose (at each one my end goal is the same). However, I’m not particularly hung up on unity of identity (it “makes sense” for the person or group that I’m nominally controlling to be making that decision). And even less so for unity of simulation (that whoever is doing the action does so in a way that matches what their historical counterpart would have done).

The definition is without “part of”. Since not the whole behavior of the invaders is modeled in the invader phase (smaller parts of it are modeled through events) even the invader phase system only models “part of” the behavior. Most of it, sure, but not the whole.

The aides is that any mechanic that models part of the behavior of an opposition can feasibly be called AI. The event cards actually make the invaders more lifelike and unpredictable and are part of how they are perceived as an active opositor by the player (as any designer knows, AI is more about player perception of “active” opposition than actual implementation, which might be a reason why you draw a pretty definite line).

I know programmers and designer that would say what you call AI in Spirit Island is not AI but a random system with no heuristics and thus not AI.

Definitions are important because otherwise it’s just assigning subjective value. What would be your definition of AI in a board game other than a judge’s definition of porn?

I’m with Juan on this one – in the context of a solitaire boardgame, I don’t see a meaningful mechanical distinction between ‘AI’ and the rest of the mechanics. You have player decision points, and then you have everything else that operates by some sort of mechanism to bring you to the next player decision point.

Talking about AI makes sense for a system that exists separate from the game itself, and that tries to use information about the game state to make decisions and “play the game” in more or less the same way that a player would, obviously with mixed results.

The opposition systems in boardgames are inherently asymmetrical and not playing the same game as the player. They should be judged not on how “smart” they are, but on how effectively they result in varied and interesting decisions for the player to make.

I feel like there are two elements interwoven in the conversation here. I’m struggling with Sherman Leader because it’s both ambiguous and incomplete. I’d be fine with your example because it gives me clarity and completeness.

Likewise, if the Sherman Leader rules stated “choose the German action to your advantage”, that’s removed both the ambiguity and the completeness. I know how the designer intended the game to be played and I can move forward.

If the rules said, “choose the best action for the Germans”, it’s clear but incomplete as a solitaire system designed to play against me.

As an aside, how you interpret the “you choose” cases seems to matter a lot in Sherman Leader. I’ve started another battle and rewritten the “you choose” decision trees to be more favorable to the Germans. In two turns I’ve already lost an irreplaceable and expensive Wolverine tank instead of a low-cost expendable Stuart. That’ll have a long term impact on how the campaign plays out. One example is only one example, for sure, but over the course of a campaign I’d bet the difficulty really forks over what you do with the “you choose” decisions.

I feel like I’ve wandered into crazypants territory here. I’ve got @Juan_Raigada trying to call out Spirit Island as a game in which you make decisions on the AI’s behalf. It isn’t. And then I’ve got @Thraeg calling a game’s lack of tie-breaker as “a valid design approach” to AI.

I’m going to stop you right there and disagree. Yes, the entirety of the AI behavior is modeled in Spirit Island. I never have to make decisions on its behalf. And, no, event cards don’t count. Event cards are a system that was added to the game to make it less deterministic, not to force the player to assume the role of the invaders.

Pfft, easily. The AI is the autonomous system that pushes back against you winning. But you seem to have decided that AI includes anything that involves a decision, so by your circular logic, the AI necessarily involves player input. I get the feeling you’re just arguing in favor of any definition that supports your claim about Spirit Island.

Now you’re just making excuses for half-assed game design. Look, if you want to play a solitaire game full of “non-obvious answers that require thinking”, you’re going to have a ball playing chess with yourself. That’s going to give you all the non-obvious answers you ever wanted in a solitaire game!

Seriously, though, your example is terrible. You’ve convinced yourself that Andrew Parks’ loosey-goosey “enh, just let the player decide when it’s a tie” is some kind of design concept. In which case, you’re going to love Sherman Leader!

I have read this paragraph several times and I have no idea what you’re trying to say and how it applies here. But, sure, I’m all for unity of purpose. So agree to agree?


I feel bad that you’re having to play Sherman Leader. There are so many better examples of solitaire wargames, and I know you own some of them!


No, I’m not saying AI is anything that involves a decision. I’m saying that AI can be considered (under some definitions) the totality of systems that model opposition, and in Spirit Island that includes some of the events.

Playing the Spirits is where most decisions are, and that’s clearly not AI by any definition, but once you get into systems that do not model player avatars but opposition avatars the distinction is fuzzy. Most informal polls I supervised on the courses I taught about this subject seem to point that people fall on both sides of that line, depending on whether they focus more on what’s being modeled (they consider more systems as AI, to the extreme as saying there’s no meaningful distinction once you leave the systems that clearly model the player avatar) or whether they focus on the experiential execution of the systems by the player (with some going as far as considering systems with little or no heuristics and limited “reading” of the board -as the invader phase in Spirit Island- as “not AI” due to the very “non-intelligent, non-reactive” nature of the process -it’s more a random-rule cellular automata, something no programmer would ever consider “AI”-).

It’s not a simple concept to define, specially when applied to games, very specially when applied to board games.

The discussion is not dissimilar to the distinction between puzzle and game. There’s a line there, but depending on perception and underlying assumptions, people are going to place it at different points.

I was trying to come up with terminology to disambiguate separate, but related concepts about what bothers different posters about solitaire game design, so that we can avoid talking past each other. It seems that I failed! Let me see if I can expand on it a bit.

Unity of Simulation: What @TheWombat is advocating here. When making decisions about an opposing force’s actions, pick based on your best understanding of what they would have done historically. The priority is simulating reality, not winning the game for either side.

Unity of Identity: What you seem to be advocating here. If the game ever asks you to make decisions about an opposing force’s actions, throw it in the trash because that’s a mortal design flaw. It’s important that the player has a clear identity in terms of who or what they’re controlling in the game. If the player controls side X, and side X wouldn’t logically be making a particular decision, then the player shouldn’t be either.

Unity of Purpose: What I am most concerned with. When making decisions about an opposing force’s actions, pick based on what will be most helpful for me reaching my goal (achieving victory for my side). My purpose is the same, whether I’m making choices about my own forces or the enemy forces. It’s the designer’s job to constrain the system such that this doesn’t become degenerate or boring.

Note that I’m not saying that the system should include decisions that the player makes for opposing forces. I agree with you that in general it’s more thematically elegant to design to avoid that. Just that those decisions don’t particularly bother me unless they want me to pick what’s historical, or optimal for the opposing force, against my own interests.

This would be the diametric opposite of Unity of Purpose, and is exactly what I’ve been arguing against this whole time! Make one move whose purpose is “victory for white”, then another whose purpose is “victory for black”, back and forth forever.

By contrast, going back to Sherman Leader where this discussion started, if I were to make a bunch of moves of Allied units and then some constrained targeting decisions about who the Germans shoot at, then as long as my ultimate goal for both of those types of decisions is “victory for the Allied side”, Unity of Purpose is not violated.

Top post, those definitions are something I will use in future…

I got nothing. :)

I think DA is one example of a deliberate mechanic, where player choice is an intended part of the enemy AI - but I too really dislike ambiguity in the rules with AI action selection and resolution. I want to play against the game, not against myself.

I was playing Imperium recently, which is civilization-ish deck/tableau builder that has an AI* for every nation in the game (if you count both boxes that’s 16 AIs). It can have up to six cards in it’s hand. There are six stacks in the market. The game comes with one six sided dice… :)

So ultimately tie breakers can always eventually come down to the card indicated by the dice, or the lowest slot number, or the most recently acquired cards. If the AI attacks me, I still choose which of my cards to discard, but this is how it works in multiplayer also.

Not sure I have a point is, just wanted to mention a cool game that does head-to-head AIs well in a genre that often doesn’t! :)

*Not the pedantic academic definition of AI, but ‘automa’ as they tend to called in board games, i.e. systems that substitute for a human player in some way.

Great post, I like your thinking.

Aren’t you supposed to play wargames solo without any solitaire rules? Sheesh.

Back in the 70s as a teen I subscribed to Strategy and Tactics magazine where they mailed you a magazine with a game every two months. None of friends would go near those games, so this is exactly what I did, I played solo without solo rules, simply by playing against myself.

I’m not sure if it was the 70s or 80s when they started putting a solitaire suitability rating on boxes along with the complexity rating.

No worries, and thanks. I’ve committed to finishing the campaign, only have 2-3 battles left, and I’m enjoying the entertainment value. I’m still reorienting myself to board wargames, and this is a gentle step forward. Complexity is low, not a lot of edge cases, and games play fast.

I’m looking forward to exploring more complete solitaire systems. Sherman Leader has just a few rules. It’s hardly a system compared to the Erasmus 12-page decision tree AI-bot (PDF) for Empire of the Sun

Depends. Most of the time I played both sides, swapping hats as it were, so the there was no need for solitaire rules. Sometimes, though, I would write up guidelines for one or the other side, and attempt to stick to them. I still do that sometimes for computer games where I play both sides, like the John Tiller stuff.

:( That just reminded me of his passing. It looks like WDS will be continuing to work on Tiller games though with the release of Kiev '43, and apparently other games in development.

I think I’m perfectly comfortable where a designer has designed the bot’s actions and decision tree’s down to a point where once the instructions say “player choice” the decision level you are making is low enough that it has absolutely no significant impact on the game.

I’m not really bothered about going down an increasingly elaborate flowchart/list of stuff simply to break a tie between two options that effectively the bot doesn’t care which one it chooses. I don’t believe that’s a failure of design that’s simply using the human player to simplify the execution.

Yes, I knew John personally, though I had not seen him in a few years, and was quite saddened to hear of his death.

WDS does the Panzer Battles games too, and these are IMO a step up in terms of overall design and operation from the venerable Panzer Campaigns titles, even with the modest upgrades those are getting. The next PB game is about the battles around Moscow early in the war and looks interesting.

Which I’ve left on my shelf for a year now without even looking at it!