Announced in the Pokémon Direct today, Pokémon Ultra Sun and Ultra Moon are two new mainline entries into the storied Pokémon franchise. Taking place in the Alolan islands from the previous entries, Pokémon Sun and Moon, the new versions follow an alternate story on the islands. Each will feature new Pokémon and add existing Pokémon to the island for players to discover.

Previously it was predicted that the next entry into the Pokémon series would be released on Nintendo Switch, with the much rumoured ‘Pokemon Stars’ expected to be announced. The rumour-mill claimed it would be released in a similar manner to how Pokémon Crystal, Emerald and Platinum were released, combining the two games while sometimes adding a unique twist to the story.

It comes as no surprise that many Pokémon fans were disappointed with the announcement: At the moment of writing, Pokemon Ultra Sun and Ultra Moon are 3DS exclusive, shattering hopes that Pokémon ‘Stars’ or at very least a Switch port, would be the big announcement Nintendo so heavily hinted at.

When considering Nintendo and The Pokémon Company’s decision to focus these games on the 3DS family of consoles, one immediate factor becomes clear: Install base. The Nintendo 3DS has sold 60 million units, and the New Nintendo 2DS XL has been announced for release on July 28, 2017. It comes as no surprise that Pokemon Ultra Sun and Ultra Moon are and should be released on the 3DS hardware family.

Pokémon Sun and Moon sold just over 15 million copies as of March 2017. This made Pokémon Sun and Moon the second best selling games just behind Pokémon X and Y. Taking those values into consideration, lets compare this to the Nintendo Switch: The install base for the console stands somewhere around 4 million units, due mostly to competition for parts limiting the number of Nintendo Switch’s the company can make. That’s less than 1/12th of the 3DS install base. Even with Nintendo’s plans to increase production to 20M units this year, it would still pale in comparison to the well established 3DS.

Even at a 100% attachment rate, the sales on Nintendo Switch wouldn’t be able to support the demand for a new, exclusive Pokemon release. Even a cautious prediction would be more than double the current install base of the Switch, and by the time production could meet the demand, the game would be old, well past the crucial launch window where games sell their fastest.

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So it’s established why it’s on 3DS and not Switch alone, but why not both? That comes down to the intricacies of game design. The most likely reason as to why Pokemon Ultra Sun and Ultra Moon (probably) won’t appear on both the Nintendo Switch and 3DS relies on the simple fact that the 3DS has two screens, whereas Nintendo Switch has one. While this doesn’t seem too important on the surface, as the developers could simply move the bottom screen utilities into a menu on the top screen, they would then have to consider how to interpret the full interactivity of the two screen system onto one screen without too much sacrifice. This becomes tricky when trying to ensure that things like petting minigames work for both modes of Nintendo Switch, and its various control schemes, to enable a full, polished release.

That’s really the only justification one can find for these games not releasing on the Nintendo Switch in addition to the 3DS. As for announcing an all new Pokémon mainline RPG that’s exclusive to Nintendo Switch, fans will likely have to wait a while. Such a game would need to be built from the ground up, on a platform with enough owners to support the usual Pokemon demand. Thanks to the scarcity of parts, it may take a while for the Nintendo Switch to reach that point. Until then, Pokemon will be tied to 3DS, exclusive or otherwise.

That may be a bitter pill for Nintendo fans to swallow, and it may come across as The Pokemon Company being too lazy to port the games to Nintendo Switch in spite of the hardware differences, but Nintendo could still announce a Switch version at E3 2017. Especially in light of the almost universal backlash to the latest Pokemon Direct.

Nintendo’s “Spotlight” Livestream will be on 9am PT, 12pm ET on June 13 2017.