Strategies in social deduction games

Here I will describe what I believe to be some basic and universally applicable strategies across social deduction games. 

IMO these are fairly easy for a beginner to pick up, allowing them to enjoy the game better. They are also easy for a veteran to subvert, and thus push their local metagame out of a stale equilibrium. 

The intention of this post is not to be prescriptive: I don't aim to tell people how to enjoy the game, and people should play games how they want. However, I do want to outline some 'basic' strategy here, since it is the foundation of what I consider to be 'advanced' strategy (discussed at the end). 

Universal game mechanics

Most social deduction games have the following components:

• Day and night cycles. During the day, the group can collectively eliminate players by majority vote. Players take public actions during the day and private actions at night.
• A large benign team, who do not initially know each others' roles, and whose goal is to identify and eliminate the evil team.
• A small evil team, who start out knowing each other. Typically, there is one 'leader' and several 'supporters'. The leader can eliminate players secretly during the night. Their goal is to eliminate the benign team. 

Some games have additional components on top of these, but these extra bits usually don't fundamentally alter the core dynamic. 

Object-level vs social information 

There are two sources of information in social deduction games:

• Object-level information, derived from game mechanics. E.g. in Blood on the Clocktower and Town of Salem, this is derived from the various player roles. In Among Us, this is derived from crewmate tasks.
• Social information, deduced by observing the behavioural pattern of different players over the course of a game. E.g. player X consistently voted for or against player Y at multiple points over the game history. 

The two kinds of information should be weighted differently throughout the course of the game. 

• Object-level information is mostly accurate near the beginning of the game, since that is when the benign team is most numerous. Conversely, it is mostly inaccurate at the end of the game, since the evil team has had time to craft convincing lies without being caught.
• Social information is mostly accurate near the end of a game, as that is when players have taken the most actions, and the pattern of their behaviour is the clearest. 

First-order strategies

These strategies are 'first-order' because they do not assume detailed knowledge of opponent's policies, and aim to be robust to a wide variety of outcomes. Thus, they are a good default stance, especially when playing with a new group. 

Benign team:

• Share information early and often. Collectively pooling information is how you find the truth.
• Share concrete information as much as possible. Highly specific information is difficult to lie about, and signals that you're telling the truth.
• Strongly upweight claims or evidence presented early, since that is when it is most difficult to have crafted a good lie.
• If someone accuses you, avoid being defensive. Seek clarification, since more information usually helps the group. Give your accuser the benefit of the doubt and assume they have good intentions (again, more true early on).
• Pay attention to behavioural patterns. Do people seem suspiciously well-coordinated?
• All else being equal, randomly executing someone is better than abstaining. Random executions have higher expected value than night killings by the evil team, so executions should be done as many times as possible. 

Evil team:  

• Maintain plausible deniability; avoid being strongly incriminated by deceptive words or in-game actions.
• Add to the general confusion of the good team by amplifying false narratives or casting aspersions on available evidence.
• Try to act as you normally would. "Relax". Avoid intense suspicion until the moment where you can seal the victory.
• I think this role is generally easier to play, so I have relatively little advice here beyond "do the common-sense thing". Kill someone every night and make steady progress. 

Common mistakes

Common mistakes for the benign team

• Assuming the popular opinion is correct. The benign team is often confused and the evil team is coherent. Thus the popular opinion will be wrong by default.
• Casting too much doubt on plausible narratives. Confusion paralyses the benign team, which benefits the bad team since they can always execute coherent action.
• Being too concerned with edge cases in order to be 'thorough'. See above point.
• Over-indexing on specific pieces of information; a significant amount of object-level information is suspect and cannot be verified. 

Common tells for the evil team.

• Avoiding speaking much or sharing concrete information. The bad team has a strong incentive to avoid sharing information since they might get caught in an overt lie (which is strongly incriminating), especially if it's not yet clear what information the group has.
• Faulty logic. Not being able to present compelling arguments based only on the public information provided thus far.
• Being too nervous / defensive about being accused. Being overly concerned about defusing suspicion, e.g. via bargaining ("If I do X, will you believe me?") or attacking the accuser rather than their argument.  
• Not directly claiming innocence. Many people avoid saying 'I'm on the good team' or similar direct statements, out of a subconcious reluctance to lie. When accused, they either 'capitulate' ('I guess you've decided to kill me'), or try too hard to cast doubt on the accuser.
• Being too strongly opinionated. Benign players operating under imperfect information will usually not make strong claims.
• Seeming too coherent. Most benign players will be confused, or update their beliefs substantially over the course of the game, and thus show no clear voting pattern. 

None of the above mistakes are conclusive in and of themselves, but multiple occurrences form a behavioural pattern, and should increase suspicion accordingly. 

Also, most of the common tells also qualify as 'common mistakes for the benign team', since benign teammates doing these things makes them present as evil.  

Advanced (higher-order) strategies 

First-order strategies are what usually emerge "by default" amongst players, because they are relatively simple and robust to a wide variety of opponent strategies. 

Higher-order strategies emerge when players can reliably predict how opponents will act, and then take adversarial actions to subvert their opponents' policies. E.g. an evil player might take actions which are detrimental to themselves on the surface level, in order to gain credibility with the benign players. But this will only be worthwhile if doing so has a large and reliable effect; ie if the benign team has a stable strategy. 

Most players never get good at executing the first-order strategies and so most local metagames never evolve beyond these first-order strategies. That is a shame, because I think social deduction games are at their best when they involve higher-order considerations, of the "I think that you think that I think..." kind. 

The ultimate goal: just have fun. 

Again, the intention of this post is not to be prescriptive, and people should play games how they want. Many people might not find the kind of gameplay I've outlined to be fun. 

But for the subset who do, I hope this post serves as an outline of how to create that fun reliably.