It does not matter at all. As long as the game is a pixel art game. And Udemy is not a game engine. It is an online learning platform with various courses covering various subjects. The prize here is a course on pixel art. You might have confused Udemy with Unity.
I don't quite understand the context of your question, so I'll do my best to answer. Firstly if you mean the jam, your game must be a pixel art game in one form or another to be accepted in the jam, since this is the Pixel Jam.
If you are making a 2D game, the graphics must be in pixel art style, and if you are making something 3D, one way to make it comply with the pixel art rule is to make the game textures low-res pixel art textures.
If you meant the Udemy prize, It's a learning course that teaches you best practices in creating your own pixel art for games. It's basically an online class.
