A Nintendo Switch 2 Game-Key Card looks like a retail cart and sits in the same slot. It does not hold the full game. It holds a key. You download the game once, then you keep the card inserted to play. That is Nintendo's official description, not a forum theory.
Furukawa's words (Nintendo IR)
At Nintendo's shareholders Q&A, president Shuntaro Furukawa answered concerns that Game-Key Cards feel like fake physical:
The game-key card used for Nintendo Switch 2 does not contain the full game data for the game itself; instead, it stores a key to activate the software. An internet connection is required for downloading the data for the game the first time you play it. Subsequent gameplay does not require an internet connection, but the game-key card must be inserted into the system.
Why Nintendo says it exists:
This is one of the new software distribution methods we have introduced to accommodate the larger game data sizes on Nintendo Switch 2 compared to Nintendo Switch.
And the publisher-relations closer:
Software can be released in various formats, and we will continue to work closely with software publishers on many fronts to ensure that they actively support our platform.
Source: Nintendo Co., Ltd. IR Q&A summary (English translation of the Japanese original).
Game-Key Card vs full game card vs pure digital
| Format | What is on the plastic | First launch | Offline after install | Can you trade the card |
|---|---|---|---|---|
| Full game card | Game data on cart | Play from cart (size permitting) | Yes, with cart inserted | Yes |
| Game-Key Card | Activation key only | Requires internet download | Yes, but card must stay inserted | Yes (you are trading the key) |
| eShop digital | No plastic | Download license | Yes, under account rules | No used market |
