My feature request is to add a 3D game engine in scratch, similar to unity but maybe simpler.

As I have learned from the official list of rejected scratch features page, I think it's a good idea to make 2 modes: first one being the simpler 2D mode. And the second one being the 3D mode, which older users with more experience could choose to prefer. This still keeps it simple.

This is a good idea because scratch projects attempting to render in 3D are often inefficient and slow, and require thousands of blocks of code.

Take crystal seeker for example, it has tens of thousands of blocks, most of them just for rendering and incredebly complex calculations. If it was built in a 3D engine then even a beginner can make crystal seeker, and with better visuals. They can also use 2D sprites if they want.

If you disagree, then please tell why this might be a bad idea.

Thanks for the suggestion however, the Scratch Team has already considered this rejected for the following reason:

The Official List of Rejected Suggestions wrote:

1.7 3D Scratch
A 3D Scratch interface, involving a z-axis in the project stage, could make it easier to create 3D projects. However, Scratch is a language that is designed to be as easy as possible for beginners to learn. The purpose of Scratch is to teach beginners basic programming concepts, which is best accomplished with a 2D interface. Adding a 3D interface could make Scratch more difficult to learn and teach. This includes having a separate website for 3D Scratch. This suggestion also includes the possibility for virtual-reality “Scratch VR” features, where a lot of the same difficulties come up; for more information, see this post.

For those who are interested, it may be worth checking out Snap's 3D Beetle extension or CreatiCode. They are block-based programming languages similar to the Scratch editor, but with 3D features. There is another similar program to Scratch that contains block programming with 3D features, called Starlogo TNG.

In the future, you can check out The Official List of Rejected Suggestions before making a suggestion.