Exploiting the Weaknesses of the State-of-the-Art Collectible Card Game Agent ByteRL

Core Concepts

The state-of-the-art agent ByteRL in the collectible card game Legends of Code and Magic is highly exploitable, leaving room for further improvement.

Abstract

The paper investigates the strength and weaknesses of the state-of-the-art agent ByteRL in the collectible card game Legends of Code and Magic (LOCM).
The key highlights are:

LOCM is a two-stage game consisting of a deck-building (draft) stage and a battle stage. The paper focuses on the battle stage.

The authors used behavior cloning to pre-train a policy network to mimic the behavior of ByteRL. This yielded an agent that was almost on par with ByteRL's performance.

The authors then fine-tuned the pre-trained agent using reinforcement learning (RL). They were able to match or even outperform ByteRL's performance on hundreds of deck pools.

An ablation study showed that the behavior cloning pre-training was beneficial for the subsequent RL fine-tuning, as it allowed the agent to reach a high win rate much faster compared to training from scratch.

The authors identified several next steps, including training a separate network for the draft stage, scaling the networks further, experimenting with different architectures, and incorporating the value function during the supervised training phase.

The authors also plan to explore automatic curriculum learning during the RL fine-tuning phase, where the number of deck pools is gradually increased.

Stats

The game Legends of Code and Magic (LOCM) version 1.5 has approximately (120 * 119 * 118)^30 ≈ 1.33 * 10^198 possible decks.
LOCM version 1.2 has 160 available cards, resulting in approximately (160 * 159 * 158)^30 ≈ 1.33 * 10^198 possible decks.

Quotes

"Even though Legends of Code and Magic is considered a small CCG compared to Magic: The Gathering or Hearthstone, it is by no means a small game."
"LOCM 1.5 and its procedural generation of cards changed that. The number of possible decks is even larger and practically infinite, and the agents now must learn to generalize and deal even with unbalanced cards (e.g. lethal cards with zero cost)."

Key Insights Distilled From

Learning to Beat ByteRL: Exploitability of Collectible Card Game Agents

by Radovan Halu... at arxiv.org 04-26-2024

https://arxiv.org/pdf/2404.16689.pdf

Deeper Inquiries

How can the draft stage be effectively trained to produce strong decks without relying on ByteRL?

Training the draft stage to produce strong decks without relying on ByteRL can be achieved through various techniques. One approach is to implement a neural network architecture specifically designed for the draft stage, utilizing one-dimensional convolutions and recurrent layers to capture the complexity of deck-building. By training this network on a large dataset of draft decisions and outcomes, the model can learn to select cards that synergize well and create powerful decks. Additionally, incorporating reinforcement learning algorithms tailored to the draft stage, such as Monte Carlo Tree Search or policy gradient methods, can help optimize the deck-building process. By iteratively improving the network's ability to predict strong card choices based on the available pool, the draft stage can be effectively trained to produce competitive decks independently of ByteRL.

What other techniques, beyond behavior cloning and reinforcement learning, could be used to further improve the agent's performance against ByteRL?

Beyond behavior cloning and reinforcement learning, several techniques can be employed to enhance the agent's performance against ByteRL in collectible card games. One approach is to incorporate self-play mechanisms, where the agent competes against itself to iteratively improve its strategies and adapt to different playstyles. Evolutionary algorithms can also be utilized to evolve evaluation functions or optimize deck-building strategies, allowing the agent to discover novel and effective tactics. Additionally, meta-learning techniques can be applied to enable the agent to quickly adapt to new opponents and environments, enhancing its adaptability and robustness. By combining these advanced techniques with deep reinforcement learning, the agent can further refine its decision-making processes and outperform ByteRL in complex game scenarios.

How could the insights gained from exploiting ByteRL's weaknesses be applied to improve the design and balance of collectible card games in general?

The insights gained from exploiting ByteRL's weaknesses can be valuable in improving the design and balance of collectible card games. By analyzing the vulnerabilities and exploitable patterns in ByteRL's gameplay, game developers can identify potential flaws or imbalances in the game mechanics. This information can be used to refine card abilities, adjust game rules, or introduce new mechanics to create a more engaging and balanced gameplay experience. Furthermore, understanding how agents like ByteRL can be exploited can lead to the development of anti-cheating mechanisms and fair play guidelines to ensure a level playing field for all players. By leveraging these insights, game designers can enhance the strategic depth, diversity, and fairness of collectible card games, ultimately enriching the overall gaming experience for players.