Ludax: A GPU-Accelerated Domain Specific Language for Board Games
Graham Todd, Alexander G. Padula, Dennis J.N.J. Soemers, Julian Togelius

TL;DR
Ludax is a GPU-accelerated domain-specific language for board games that enables fast simulation and integration with deep learning, facilitating research in AI and reinforcement learning.
Contribution
It introduces Ludax, a novel game description language that compiles into hardware-accelerated code, combining flexibility with high performance for AI research.
Findings
Ludax achieves significant speedups in game simulation.
It seamlessly integrates with deep learning frameworks like JAX.
Demonstrated effective training of RL agents using Ludax.
Abstract
Games have long been used as benchmarks and testing environments for research in artificial intelligence. A key step in supporting this research was the development of game description languages: frameworks that compile domain-specific code into playable and simulatable game environments, allowing researchers to generalize their algorithms and approaches across multiple games without having to manually implement each one. More recently, progress in reinforcement learning (RL) has been largely driven by advances in hardware acceleration. Libraries like JAX allow practitioners to take full advantage of cutting-edge computing hardware, often speeding up training and testing by orders of magnitude. Here, we present a synthesis of these strands of research: a domain-specific language for board games which automatically compiles into hardware-accelerated code. Our framework, Ludax, combines…
Peer Reviews
Decision·Submitted to ICLR 2026
1. Novelty: Ludax successfully combine PGX with Ludii to allow them compliment to each other and achieve both generality and acceleration via principled code generation. 2. Usability: The environment is able to directly fit into JAX-based RL pipelines and the game descriptions closely mirror natural language lowering the technical requirements for domain experts and researchers to prototype variants. The scalability and structured description make it possible to train LLM for game generation, r
1. Hard Limitation: Limited to single-piece, placement/capture games on regular boards. No support for multi-piece types, stacking, promotion, or irregular geometry. 2. Benchmark Analysis: No memory profiling or compile-time analysis. No ablation of optimizations (precompute vs. naive). No large-board stress test (e.g., 19×19 Pente). 2. LLM integration: No demonstration of LLM-guided search over Ludax space (e.g., evolving win conditions) or RL generalization across generated variants.
The paper is well written, and the motivations are clear. Games are certainly important in the history of AI, and have led to many breakthroughs. Further, a language like Ludax has uses beyond games, and can express a variety of problems, and also be useful in analyzing RL generation. or rapid testing on procedurally generated game environments. Impressively, the speed of Ludax games is comparable with specific game jax implementations. The supplemental materials were clear, and the code was eas
My main issue with the paper is its limited novelty. While section 3.4 does discuss some non trivial differences from Ludii, fundamentally Ludax is simply a Jax port of Ludii. While this is certainly a very useful achievement, and I am sure it will be used, I do not believe that slightly modifying an existing tool to work with Jax merits a paper at ICLR. I commend the authors for their quality work. and recommend submitting to a more appropriate venue.
- Ludax combines the representation power of Ludii for board games with the performance improvements of a bespoke implementation written by hand in PGX. This strategy will allow researchers to investigate a wide range of existing board game dynamics quickly and implement new games amenable to accelerated training. - The performance profiles comparing Ludii, Ludax, and PGX illustrate nicely the level of training throughput achievable using Ludax, as shown in Figure 2. - The fidelity of the game d
- The biggest weakness is the lack of breadth of the current features of Ludax compared to Ludii. Although Ludax does provide support several games, the contribution would be significantly higher if more environments were supported, given the number of games available in Ludii. - The presentation of Ludii in Section 3 is extensive, but an extensive portion is dedicated to describing existing components instead of focusing on the contributions of Ludax. - This paper seems like an interesting dire
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Taxonomy
TopicsArtificial Intelligence in Games · Reinforcement Learning in Robotics · AI-based Problem Solving and Planning
