USPTO Rejects All 26 Claims of Nintendo’s ‘Summon-and-Battle’ Patent — Ripple Effects on the Palworld Litigation

The Patent and the “Summon-and-Battle” Mechanic

On April 2, 2026, the U.S. Patent and Trademark Office (USPTO) issued a Non-Final Office Action rejecting all 26 claims of Nintendo’s U.S. Patent No. 12,403,397. The patent, which covers a game mechanic in which a player character summons a sub-character to fight or perform tasks on the player’s behalf, is closely tied to the Pokémon and Pikmin franchises. The outcome of this reexamination is attracting intense scrutiny from across the gaming industry.

Patent No. 12,403,397, granted in September 2025, covers a game system in which a sub-character is called by a player character to engage in combat or complete assigned tasks. This mechanic is central to Pokémon’s battle system and to the Pikmin series’ mechanic of commanding subordinates to clear obstacles. Critics had questioned from the outset whether such a mechanic was patentable, arguing that the concept of summoning characters to fight has existed since the earliest days of video games.

Basis for Rejection: Prior Art from Nintendo, Konami, and Bandai Namco

In a notable irony, the prior-art references cited in the Non-Final Office Action include Nintendo’s own earlier patent applications. The USPTO determined that prior applications filed by Nintendo, Konami, and Bandai Namco disclose the technical features claimed in the patent under reexamination — meaning the “summon-and-battle” mechanic was already known in the art and fails to satisfy the requirements of novelty or non-obviousness.

Under patent law, a claim must satisfy two core requirements: novelty (the invention must not have been previously disclosed in the prior art) and non-obviousness (the invention must not have been readily deducible from the prior art). The USPTO’s rejection indicates that at least the novelty requirement is not met.

An Unusual Procedural History: Director-Initiated Reexamination

The procedural history of this patent adds another layer of significance. In November 2025, USPTO Director John A. Squires ordered a Director-Initiated Reexamination of the patent — the first time the USPTO had exercised this authority since 2012. Ordinarily, reexamination is initiated by a third-party petitioner such as a competitor, making a director-ordered reexamination extraordinarily rare.

The director’s decision was prompted by mounting concern from the gaming industry and legal community about overbroad patent claims. The question of whether fundamental game mechanics can be monopolized through patent protection is a practical issue of great importance to game developers worldwide.

Implications for the Palworld Litigation in Japan

The case draws heightened attention because Nintendo has filed a patent infringement lawsuit in Japan against Pocket Pair, developer of Palworld, asserting this patent (and related patents) and seeking an injunction. A determination on the U.S. patent’s validity could indirectly influence the Japanese proceedings.

However, U.S. and Japanese patent systems operate independently, so a USPTO rejection does not automatically invalidate the corresponding Japanese patent. The Japan Patent Office and Japanese courts assess validity on their own merits. That said, the confirmed existence of prior art establishing that “summon-and-battle” mechanics were already known may be cited in Japanese invalidation proceedings or litigation, making this a potentially significant precedent.

Nintendo’s Options: Amendment or Argument

In response to a Non-Final Office Action, the patent owner typically has two months (extendable) to file a response with the USPTO. Two principal strategies are available. First, Nintendo could amend the claims to narrow their scope so as to distinguish the prior art. Second, Nintendo could argue that the cited prior art does not in fact disclose the currently claimed features.

If Nintendo pursues amendments, the claims’ scope could be significantly reduced, potentially requiring strategic adjustments to both the Japanese litigation and related licensing negotiations. Whether an argument-only approach can succeed depends on the strength of Nintendo’s technical distinctions.

The Fundamental Problem with Game-Mechanic Patents

This case crystallizes a broader tension in the patent system: whether abstract game mechanics — as opposed to specific technical implementations — should be protectable. Courts and patent offices in the United States have grappled extensively with what constitutes patentable subject matter under 35 U.S.C. § 101, particularly for software and interactive entertainment. The USPTO’s rejection reinforces the principle that well-known interactive concepts cannot be newly patented simply by describing them in a game context. For the gaming industry at large, the case is a reminder that mechanic-level patent claims face significant validity risk.