Hard AI Just Got Stronger – Win Rate Reaches 60.3% (v0.11)

In this update, the Hard AI’s win rate against Normal in Watch Mode has been improved from 57.7% to 60.3% (+2.6%).

Below are the main improvements:

■ Strategic Decision-Making

• Introduced an optimized sequence that minimizes the risk of completing Rainy Four Lights

• Improved early Koi-Koi stop decisions using Sake Cup when expected value is low

• Strengthened continuation decisions when success probability is high and risk is low, even at low scores

• In losing situations (final round), the AI now selects only moves that allow for a comeback

• Overall improvement in Koi-Koi stop decision accuracy

■ Evaluation Function Improvements

• Refined scoring evaluation for TANE / TAN / KASU

• Fixed incorrect expected value estimation for Red Poetry Ribbons (Akatan)

• Added missing evaluation for “next-turn secure potential”

■ Risk Management Enhancements

• Increased release bonus for “all remaining cards are KASU” months when opponent’s KASU win is unlikely

• Improved risk handling for leaving collectible but unlocked Susuki Light cards

■ Fallback Behavior Adjustments

• Reduced Greedy Fallback overreach to prevent good moves from being overridden

• Fixed low-value actions during Rapacious Fallback

■ Reduction of Suboptimal Plays

• Prevented unnecessary discarding of high-value cards

• Fixed low-value plays (e.g., discarding Sakura Light)

• Improved low-value drop decisions

■ More Natural Behavior

• Improved delayed “Agari” behavior after Koi-Koi

For detailed changes (in Japanese), please see:

https://github.com/suzukiplan/open-hanafuda-ai/milestone/2?closed=1

With the win rate now exceeding 60%, the next update will introduce Hard Mode (Human vs Hard).

We will continue improving the win rate of the AI (Open Hanafuda AI) even after the implementation of Hard Mode. In addition, we plan to integrate the latest version of Open Hanafuda AI into Battle Hanafuda as its reference implementation.

https://github.com/suzukiplan/open-hanafuda-ai