It's "crazy easy" from a programming perspective, since the engine mostly does that for you, but it still takes lots and lots of effort to create the assets for

It's "crazy easy" from a programming perspective, since the engine mostly does that for you, but it still takes lots and lots of effort to create the assets for a AAA-level game (detailed 3D models and textures for characters and environment, motion capture, NPC behaviour etc.), followed by putting everything together and testing it.