Your game must be made out of 2D sprites and/or 3D models found on the Kenney website. You cannot draw or model new assets, and you can't get them from somewhere else. The only exception are audio files (sound effects, music) and fonts, those can be custom created or source from elsewhere. If you don't adhere to this rule, you've lost the challenge.

Is it allowed to recolor sprites? Yes.

Is it allowed to crop, rotate, flip or scale sprites? Yes.

Is it allowed to create custom animations for 3D models? Yes.

Is it allowed to draw additional sprites or animations for 2D art? No.

Is it allowed to create custom materials and shaders? Yes, however textures should be sourced from Kenney assets.

Is it allowed you to use basic primitives? No, you'll find similar objects among the 3D game assets.

Is it allowed to use models, textures or other assets that come with the game engine? No.

Is it allowed to create 3D terrain? No, you'll find terrain objects among the 3D game assets.