# Engagement-Oriented Dynamic Difficulty Adjustment
## 3 Engagement-Oriented Dynamic Difficulty Adjustment
### Intervention
#### 3.2.1 Parameter Set  
Players, partners, opponents, systems, scenes, and other neutral actors are all important game elements that affect player engagement. Through systematic research of all major game genres in the game industry, the more common parameters of each genre are selected. A common adjustable parameter set is constructed based on the correlation between parameters and difficulty as well as their belonging, as shown in Table 2. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Symbol** & **Parameter** & **Description** \\ \hline C & Challenge & The stage player faces difficulties during gameplay. \\ p\({}^{S}\) & Sleep phase & The former part of the game that does not monitor churn. \\ p\({}^{A}\) & Active phase & The latter part of the game that monitors churn in real time. \\ p\({}^{U}\) & Unit phase & The minimum number of challenges that can be monitored. \\ p\({}^{T}\) & Threshold phase & The number of unit phases that can be judged to be churn. \\ T\({}^{S}\) & Sleep time & The former part of a challenge that does not monitor churn. \\ T\({}^{A}\) & Active time & The latter part of a challenge that monitors churn in real time. \\ T\({}^{U}\) & Unit time & The minimum time that can be monitored. \\ T\({}^{T}\) & Threshold time & The number of unit times that can be judged to be churn. \\ \(M\) & Threshold metric & The metric that can be judged to be churn. \\ \(F\) & Fitness & The appropriateness of difficulty settings to adapt to different players. \\ G & Gameplay time & The gameplay time for the player. \\ N\({}^{T}\) & Number of times & The number of unit times in a challenge. \\ N\({}^{C}\) & Number of challenges & The number of challenges in the game. \\ N\({}^{R}\) & Number of trials & The number of trials for the player during a challenge. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Formalized definition of churn parameters. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Correlation** & **Classification** & **Parameter** \\ \hline \multirow{4}{*}{Positive} & Partner-fixed & \multirow{4}{*}{
\begin{tabular}{c} Cooldown. \\ Number, attack, defense, health point, magic point, stamina, speed, adaptive capacity, \\ perception range. \\ \end{tabular} } \\  & Opponent-random & Luck, critical chance, hit chance, dodge chance, beneficial attribute rate. \\  & Neutral & Gameplay pace, difficulty seed, adverse time. \\ \hline \multirow{4}{*}{Negative} & Player-random & Luck, critical chance, hit chance, dodge chance. \\  & Partner-fixed & Number, attack, defense, health point, magic point, stamina, speed, adaptive capacity. \\ \cline{1-1}  & Partner-random & Luck, critical chance, hit chance, dodge chance. \\ \cline{1-1}  & Opponent-fixed & Cooldown. \\ \cline{1-1}  & Opponent-random & Adverse attribute rate. \\ \cline{1-1}  & Neutral & Hint number, beneficial time. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Common adjustable parameter set. The parameters in Table 2 are classified into six types: player-random, partner-fixed, partner-random, opponent-fixed, opponent-random, and neutral. It should be noted that player-fixed attributes are generally visible to players. Changing them directly will break the concealment of DDA, thereby reducing the player experience. A positive correlation means that the difficulty will increase as the parameter increases, while a negative correlation means the opposite. All parameters in the set are adjustable, but not all of them exist or are suitable for adjustment in practice. Game designers may adaptively choose appropriate parameters to implement player churn intervention on account of high or low difficulty. Take the Role-playing Game (RPG) and Racing Game (RAC) for instance, each combat and race can be considered as a \(C\), correspondingly. In the RPG, partners generally refer to the teammates the player meets during gameplay, while enemies in combat are typical representatives of opponents.