Abstract

Machine learning competitions such as those organized by Kaggle or KDD represent a useful benchmark for data science research. In this work, we present our winning solution to the Game Data Mining competition hosted at the 2017 IEEE Conference on Computational Intelligence and Games (CIG 2017). The contest consisted of two tracks, and participants (more than 250, belonging to both industry and academia) were to predict which players would stop playing the game, as well as their remaining lifetime. The data were provided by a major worldwide video game company, NCSoft, and came from their successful massively multiplayer online game Blade and Soul. Here, we describe the long short-term memory approach and conditional inference survival ensemble model that made us win both tracks of the contest, as well as the validation procedure that we followed in order to prevent overfitting. In particular, choosing a survival method able to deal with censored data was crucial to accurately predict the moment in which each player would leave the game, as censoring is inherent in churn. The selected models proved to be robust against evolving conditions—since there was a change in the business model of the game (from subscription-based to free-to-play) between the two sample datasets provided—and efficient in terms of time cost. Thanks to these features and also to their ability to scale to large datasets, our models could be readily implemented in real business settings.

Highlights

  • In video games, reducing player churn is crucial to increase player engagement and game monetization

  • In addition to the root mean squared logarithmic error (RMSLE) measure, we evaluated the mean absolute error (MAE), root mean squared error (RMSE) and integrated Brier score (IBS)

  • The models that led us to win both tracks of the Game Data Mining competition hosted at the 2017 IEEE Conference on Computational Intelligence and Games were based on long short-term memory networks, extremely randomized trees, and conditional inference survival ensembles

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Summary

Introduction

In video games, reducing player churn is crucial to increase player engagement and game monetization. By using sophisticated churn prediction models [1,2], developers can predict when and where (i.e., in which part of the game) individual players are going to stop playing and take preventive actions to try to retain them. Examples of those actions include sending a particular reward to a player or improving the game following a player-focused data-driven development approach. Survival analysis focuses on predicting when a certain event will happen, considering censored data In this case, our event of interest is churn, and highly accurate prediction results can be obtained by combining survival models and ensemble learning techniques. We present the feature engineering and modeling techniques that led us to win both tracks of that contest

The Data
Challenge
Evaluation
Time-Oriented Data
Autoencoders
LSTM Autoencoder
Feature Value Distribution
Feature Importance
Tree-Based Ensemble Learning
Extremely Randomized Trees
Conditional Inference Survival Ensembles
Long Short-Term Memory
Model Specification
Model Validation
Cross-Validation
Results
Discussion and Conclusions
Full Text
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