Game Design

hogwarts mystery duels: rock-paper-scissors combat design

Make no mistake, there’s a lot I don’t like about the mobile game Harry Potter: Hogwarts Mystery.  Released in 2018 as the first game under the Warner Bros. Interactive label Portkey Games, it was widely panned for its micro-transaction-heavy gameplay1, 2, 3.

In fact, the first time you run out of “spell energy” and that annoying purchase screen shows up is when you’re trapped by a venomous plant.

To some extent, this is expected of a mobile game.  And to be fair, I’ve already written about designing micro-transactions and waiting in mobile games.  I don’t intend this post to be a review of Hogwarts Mystery and its pay-to-play model — it’s been done by critics, and it’s not anything you haven’t heard before.

Instead, I want to focus on duelling in Hogwarts Mystery.  The duels use rock-paper-scissors as their mechanics, but misuse the concept.  This makes Hogwarts Mystery a great candidate for an analysis of rock-paper-scissors as combat mechanics in game design.


Using the Implicit Fairness of “Rock, Paper, Scissors” in Hogwarts Mystery Duel Design

The fundamental principle behind Rock, Paper, Scissors is that it’s a fair game.  In effect, there’s an equal chance of choosing each outcome, which has an equal power.  This is why we “roshambo” for who gets the last slice of pizza, or who has to do the dishes afterwards.

Jesse Schell writes in The Art of Game Design4:

One simple way to balance elements for fairness is to make sure that whenever something in your game has an advantage over something else, yet another thing has an advantage over that! The iconic example of this is the game of Rock, Paper, Scissors where:

  • Rock breaks scissors
  • Scissors cut paper
  • Paper covers rock

None of the elements can be supreme, because there is always another that can defeat it.


Studies on “Rock, Paper, Scissors” in Game Theory

There are, of course, many studies on Rock, Paper, Scissors, a notable one in 2014 by a group of Chinese researchers who evaluated the decisions made in playing the game5.  They compared the players’ actions to the rationality of Nash equilibrium in game theory.

In general, the researchers concluded that there are strategies to improve your chances of winning at Rock, Paper, Scissors.  In a nutshell:

  1. Winners tend to repeat what they did.  So, if you lose, play what would defeat your opponent’s move in the last round.  In other words, play the thing that didn’t show up in the last round.
  2. Losers tend to play to defeat what beat them.  So, if you win, play what would defeat the move that would beat yours last round.  In other words, play your opponent’s move in the last round.

Indeed, there is some skill to being able to predict an opponent’s next move, particularly with the advantages of playing in person or playing with someone you know.  There are additional observations that claim men often play “rock”, and that “scissors” is the least used move in tournaments6.


Take away the psychology aspect and you’re left with the design of a simple system, one that is the basis of many combat systems in games.  Let’s assume, for simplicity’s sake, that this combat system is human versus the computer, and the computer randomly chooses rock, paper or scissors on each turn.

Adaptations to “Rock, Paper, Scissors” for Combat or “Duels” in Hogwarts Mystery

In Harry Potter: Hogwarts Mystery, the three choices are “Aggressive”, “Defensive” and “Sneaky”.

  • “Agressive” defeats “Sneaky”
  • “Sneaky” defeats “Defensive”
  • “Defensive” defeats “Aggressive”

Here’s how duelling works in Hogwarts Mystery, in which one of the players is the computer.  Each player has a given amount of stamina and the goal is to reduce your opponent’s stamina to zero first.  In each round, there are two stages:

  1. Each player picks one of these three choices (“Aggressive, Defensive, Sneaky”) in a Rock, Paper, Scissors style match.
  2. The player who wins the round of “Aggressive, Defensive, Sneaky” gets to choose and execute an attack from the list of available attacks under the category they selected.

Here are the lists of spells up until Year 4.  I’ve highlighted damage in red, heals in green, and stuns in yellow.

Hogwarts Mystery Duelling Spells, Effects and Bonuses


SpellYear LearnedEffectBonus
Throw Vial0Medium reduction in opponent stamina
Expelliarmus1Medium reduction in opponent staminaChance of small stun
Incendio2Chance of large reduction in opponent stamina over time
Depulso3Large reduction in opponent stamina
Confringo4Small reduction in opponent staminaChance of medium stun



SpellYear LearnedEffectBonus
Throw Vial0Medium reduction in opponent stamina
Wiggenweld Potion1Large heal over time
Episkey2Medium healChance of medium heal over time
Petrificus Totalus3Small reduction in opponent staminaChance of medium stun
Bombarda4Chance of large reduction in opponent stamina over timeChance of small stun


SpellYear LearnedEffectBonus
Throw Vial0Medium reduction in opponent stamina
Rictusempra1Small reduction in opponent staminaChance of small stun
Flipendo2Large reduction in opponent stamina
Immobulus3Medium reduction in opponent staminaChance of small stun
Diffindo4Chance of large reduction in opponent stamina over time

Problems with Hogwarts Mystery Duels Combat Design

1. Rock, Paper and Scissors need to be equally powerful and equally useful

There’s a major design flaw in this combat system that undermines the fairness of Rock, Paper, Scissors.  In Hogwarts Mystery duels, the three options are not created equal.  Even just by looking at the names, “Aggressive”, “Defensive” and “Sneaky” imply different kinds of actions, for different reasons and with different results.

Sure enough, the available actions for each type of move are different, causing the game to be imbalanced.  For example, the only way to heal is by winning the Rock, Paper, Scissors round by selecting “Defensive”.  If I was at low stamina and desperately needed to heal, I would need to choose “Defensive” no matter what I thought would be the best move in the Rock, Paper, Scissors round.


This is very confusing because it causes a conflict in player goals.  If I prioritise winning the first round, I might not be able to strategically win the duel, since healing might not be one of the available actions under the move I chose.  But if I prioritise winning the duel, by selecting “Defensive” because I need to heal, I might not be able to win the first round and would therefore be unable to make my move win anyway.  It’s a lose-lose situation that prevents me from strategising.

In order for the two-step combat mechanics to work, players need to be able to do the same things no matter what option (“Aggressive”, “Defensive” or “Sneaky”) they chose in the first round.  As the game is currently designed, the only way to get a fair duel is to start a duel before you learn any spells, at Year 0.  The only option would be to “Throw Vial” for a reduction in your opponent’s stamina, and as long as your opponent had the same option, it would be a completely fair match.

2. If there is a clear winning choice in a list, there should not be a list

What’s more, the three lists of spells are practically unnecessary because since there are no cooldowns or material costs to cast each spell, I am always going to choose my most powerful spell when I win the first round.  This has the same effect of just having one spell that increases in power as you advance in the game, or replacing the list of spells with your most recently learned, most powerful spell.  It would certainly cut down on the complexity and be easier on Hogwarts Mystery‘s duelling UI.

The design of these two stages in combat makes duelling unnecessarily complex.  I understand the desire to use both chance (Rock, Paper, Scissors) and strategy (choose a spell) in a duelling system, but above all they need to be implemented in a fair way.


A simple fix would be to maintain both steps, but have all possible skills be useable in the second round if the player won at Rock, Paper, Scissors.  This would allow the player to strategise for each round in isolation, and therefore be able to make meaningful decisions.

3. Develop for meaningful depth instead of useless variety

Instead of developing the breadth of different types of spells, rendering many of them useless, the designers should focus on developing the depth of Rock, Paper, Scissors.  For example, they could develop more realistic AI, or “tells” that the computer opponent do that give away what they are about to play.

Or, it could measure the player’s timing and accuracy in tracing the spells or doing other skill-based tasks to determine how much damage or healing is awarded.  Right now, players can try tracing a spell multiple times with no penalty for doing it wrong, and no reward for doing it right on the first try.

Hogwarts Mystery Fails to Capture the Simplicity and Elegance of “Rock, Paper, Scissors” in its Duels

Harry Potter: Hogwarts Mystery goes about its duels very clumsily, and suffers from a common problem of doing too much.  The duelling system convolutes the elegant design of Rock, Paper, Scissors, taking away fairness and player agency.


As game designers, it’s awfully tempting to want to build on fundamentals and develop complex systems, but that may not be the best move.  The best designs are often the simplest ones, and it would do us good to remember the tried and true KISS principle: “Keep it simple, stupid.”

References Cited

  1. MacDonald, Keza. “Harry Potter: Hogwarts Mystery review: a shameless shake-down.” The Guardian, 4 May 2018. Web. 27 January 2020.
  2. Jagneaux, David. “Harry Potter: Hogwarts Mystery Review.” IGN, 4 May 2018. Web. 27 January 2020.
  3. Cooper, Dalton. “Harry Potter: Hogwarts Mystery Review.” GameRant, 14 May 2018. Web. 27 January 2020.
  4. Schell, Jesse. The Art of Game Design: A Book of Lenses. 2nd ed., CRC Press, Taylor & Francis Group, 2015.
  5. Wang, Zhijian, Bin Xu and Hai-Jun Zhou. “Social cycling and conditional responses in the Rock-Paper-Scissors game.” Scientific Reports, vol. 4, no. 5830, 2014.
  6. Poundstone, William. “How to always win at rock, paper, scissors.” The Telegraph, 1 September 2014. Web. 27 January 2020.