Is It Percival Time Yet?: a Preliminary Analysis of Avalon Gameplay and Strategy
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Is it Percival time yet?: A preliminary analysis of Avalon gameplay and strategy Yuzuko Nakamura Carnegie Mellon University 5000 Forbes Avenue Pittsburgh, PA 15213 [email protected] ABSTRACT and Morgana, creates more opportunities for blung, trust, and The Resistance: Avalon is a hidden-roles-style board game. In this strategy so we are interested in games with these four roles: paper, we use data collected over dozens of Avalon games to make • recommendations on role sets and game sizes that maximize the Merlin (good): The player with this role knows all evil roles. game-playing experience. We also evaluate the eect of various They must guide other good players to this knowledge. strategies on good and evil’s chances of winning. However, Merlin must be subtle in the way they do this due to the role of the Assassin. KEYWORDS • Assassin (evil): If good successfully passes three missions, the player with this role gets to choose one good person to Board games, hidden-role games, game design assassinate (after discussing with the rest of the evil team). ACM Reference format: If the assassinated player was Merlin, evil snatches victory Yuzuko Nakamura. 2017. Is it Percival time yet?: A preliminary analysis of from the jaws of defeat and wins the game. As such, this Avalon gameplay and strategy. In Proceedings of SIGBOVIK, Pittsburgh, PA person serves as a check on Merlin’s ability to help the USA, April 2017 (SIGBOVIK’17), 6 pages. good team. DOI: 10.1145/nnnnnnn.nnnnnnn • Percival (good): The player with this role knows who Mer- lin is. As such, they can also gain indirect information 1 INTRODUCTION about who to trust by quietly observing Merlin’s actions The Resistance: Avalon [1], like Maa, is a multiplayer game cen- and can appear to evil as a decoy Merlin. However, due to tered around hidden roles. Hidden role games involve players being the role of Morgana, Percival must rst determine which randomly assigned roles that are not revealed to other players. Merlin to trust. These games often feature two or more sides with their own win • Morgana (evil): The player with this role appears as a sec- conditions; in particular, there is frequently an evil or sabotaging ond Merlin to Percival, forcing Percival to spend some time side that attempts to blu and win people’s trust in order to win the determining who to trust, and possibly leading Percival to game, and a good (but generally information-less) side that must sabotage the good team by trusting Morgana instead of correctly guess who to trust in order to win the game. Merlin. Avalon is a two-team game themed around King Arthur: the loyal knights of King Arthur (good team) attempt to succeed three Good players who are neither Merlin nor Percival (generic good) quests (missions), and the minions of Mordred (evil team) attempt know nothing about any player other than themselves. Merlin and to be placed on the missions so as to sabotage them and lead three evil players know the full evil team. Percival knows the two people of them to fail. As such, the aim of evil is to be trusted by good who are Merlin and Morgana, but not which is which. This selective players and the aim of good is to determine who can be safely information is revealed to the appropriate players at the start of the trusted to be sent on a mission. In addition, all members of the evil game - termed the “nighttime phase” - by asking players to close team know each other (with possible exceptions). their eyes, and then open their eyes to get information or raise their Avalon in its simplest form1 features two special roles, Merlin thumb to identify themselves, as appropriate. and the Assassin. The addition of two other special roles, Percival In this paper, we seek to evaluate how rules and game size aect the funness of the gaming experience, and how dierent strategies 1Avalon may also be played without any special roles (in which case it resembles its are more or less successful for good and evil. predecessor, The Resistance). However, the main feature of Avalon are these special roles. Permission to make digital or hard copies of all or part of this work for personal or 2 GAME ANALYSIS classroom use is granted without fee provided that copies are not made or distributed for prot or commercial advantage and that copies bear this notice and the full citation 2.1 Evaluating funness on the rst page. Copyrights for components of this work owned by others than ACM 2.1.1 Ideal win ratio. One feature of Avalon is that, not only are must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specic permission and/or a the good and evil teams asymmetrical (having dierent abilities, fee. Request permissions from [email protected]. information, and objectives), but they are also of asymmetric sizes SIGBOVIK’17, Pittsburgh, PA USA (the evil team in Maa-style games needing to be a minority to © 2017 ACM. 978-x-xxxx-xxxx-x/YY/MM...$15.00 DOI: 10.1145/nnnnnnn.nnnnnnn avoid the game being trivially easy). SIGBOVIK’17, April 2017, Pisburgh, PA USA Yuzuko Nakamura Table 1: Ideal win ratios for each possible size of Avalon 2.2 Strategy game under Supposition B (making evil wins as likely as 2.2.1 Percival claims. The rules in the instruction manual are good wins). not clear on whether players are allowed to claim to be Percival. However, the role of Percival is similar to the role of generic good Game Size # Evil Ideal Good Win Chance – and unlike Merlin or the evil roles – in that claiming the role 5 2 .40 can potentially help the claimant’s team (whether good or evil). 6 2 .33 Therefore, we allow players to publicly claim to be Percival. 7 3 .43 A true Percival claim (Percival claiming Percival) can increase 8 3 .38 trust among good members but can possibly make Merlin assassina- 9 3 .33 tion easier for the evil team. We are interested in whether claiming 10 4 .40 to be Percival, and the timing of such claims, tends to help good or evil. 2.2.2 The first mission fail. Evil players have the choice whether Supposition A: Funness is maximized by maximizing uncertainty. to throw in a fail card or a success card for missions that they go In other words, we want the probability of winning to be 1=2 re- on. A sole evil player on the rst mission may decide to pass the gardless which team one is on. This means overall win chance of mission to avoid detection / suspicion for being on a failing team. good and evil must be balanced to be 1=2 for an ideal game-playing However, an early mission fail can make the evil team’s task of experience. failing three missions total easier. Supposition B: Funness is maximized by making each person’s We are interested in whether rst mission fails overall help the wins equally likely to be earned while on the good team as while good or evil team, and how the size of the rst mission factors in on the evil team. Equivalently, across all games, the good and evil to this. teams both produce roughly the same number of winners. Under this supposition: 2.2.3 Evil coordination failures. When two or more evil players are on a mission team, they each have to choose whether to throw 1 in a fail or success card, not knowing what their teammates are Pr (i is good j i wins) = Pr (i is evil j i wins) = (1) 2 planning to do. As a result, sometimes evil players may end up Or... passing the mission, or may put in more than one fail card, revealing key information about the make-up of the team. As such, a team Pr (i is good \ i wins) Pr (i is evil \ i wins) = (2) with more than one evil person is not ideal for the evil team, and Pr (i wins) Pr (i wins) they may be cautious about proposing or approving teams with Assuming player i doesn’t aect the win probability of their this make-up. team, this is the same as: How often do coordination failures happen, and how do they aect evil’s chance of winning? We investigate these questions in Pr (i is good) · Pr (good wins) = Pr (i is evil) · Pr (evil wins) (3) this paper. If pgood is the win probability for good, and G is the chance of 3 METHOD being good (i.e. the number of good roles over the total game size), A body of 38 graduate students played games of Avalon (20 of then this equation is: which played “semi-regularly” i.e. ve or more times during the data collection period). In total, 66 games were recorded although G · pgood = (1 − G) · (1 − pgood ) (4) 5 were discarded due to incomplete information, resulting in 61 games overall. G · pgood = 1 − G − pgood + G · pgood (5) All games were played using the Merlin, Percival, Morgana, and Assassin special roles. In addition, 10 of these games added the special roles Mordred and/or Oberon. p = 1 − G (6) good The following data were collected for each game: In other words, under this supposition of equalizing the portion • Number of players and role of each of good and evil wins, the ideal win ratio for win is 1 − G, or the • Approved mission teams and mission outcomes (but not chance of being evil.