Yesterday, Nintendo revealed its next console, the Nintendo Switch 2, via a short video. The clip didn’t reveal too much outside of its design and a brief glimpse of the next Mario Kart game. We did get one crucial detail, though: the system is compatible with Nintendo Switch games, both digitally and physically. There is one caveat that has fans nervous, though. Nintendo says that select games won’t be backwards compatible, but it hasn’t explained what that means yet.

While we’re in the dark about what that means, we have one reasonable guess — and it has to do with the original Switch’s most underused feature.

While the Switch is best known for its revolutionary handheld design, that’s not the console’s only unique feature. When it was announced, Nintendo put a lot of emphasis on the system’s IR sensors, which appear at the bottom of Joy-con controllers. These were supposed to be the system’s bespoke gameplay gimmick … but that didn’t go exactly as planned. Nintendo never really did much with that concept, nor did third-party developers. Only a handful of games utilize the IR sensors at all.

That may have been for the best, because the Nintendo Switch 2 doesn’t appear to feature IR sensors — or at least not in the same way that they appeared on the original Switch. If that’s the case, it’s reasonable to assume that a handful of games won’t be entirely compatible with Nintendo’s new system.

That list would include WarioWare: Move It!, Ring Fit Adventure, 1-2 Switch, Game Builder Garage, Nintendo Labo, Resident Evil Revelations, and Dr. Kawashima’s Brain Training.

There’s still a chance that these games could mostly work on Switch 2. Ring Fit Adventure only uses IR sensors to record players’ heart rates, for instance. The feature is a little more integral to games like 1-2 Switch though, so it’s hard to imagine Nintendo making those games compatible with its new hardware.

We’ll have to wait to find out what’s officially off the table. For now, all we can do is wait until April 2’s Nintendo Switch 2 Direct.