Can You Put Nintendo 2DS Games in a 3DS? (There's No Such Thing as a "2DS Game")

There is no such thing as a "2DS game cartridge." This is a common misunderstanding. The 2DS and 3DS play the exact same physical cartridges—Nintendo 3DS Game Cards.

The Facts

• 2DS is a hardware variant: Same CPU/GPU, no 3D screen, no hinge, mono speaker. Software library is identical.
• Cartridge slot is identical on 2DS, 3DS, 3DS XL, 2DS XL, New 3DS/2DS.

What Is Different

Conclusion: Any 3DS game cartridge works in a 2DS, and vice versa. They are the same platform.