Hello all! I'll be quick with this. I'm looking for an engine with a ton of assets pre-loaded into it since I don't have the resources to make my own. For example, if I could use the level editor of say, Halo, with all the textures, geometry, and other stuff loaded in, that would be great (kind of like a mod). I'm trying to make levels for 2D and 3D games. I have the latest macbook pro to use. Thank you for reading!

It's not built in to an engine, but you could possibly check out using AssetForge with your engine of choice.