You are joking right ? renderer, audio, math, physics, animation, AI, asset streaming,.... in addition to the gameplay itself, and you compare it to a medium-sized mobile app ???

Apps usually have tons of boilerplate, so pure LoC may be similar. But in density, no contest. I recently dug up an old objc app of mine and was shocked how few lines it took to send a REST request, parse and process it. Nowadays it is split into multiple files, usecases, repositories, protocols to accomplish the same. All in the name of testability or architectural “correctness”. Write that in a game and you’re fired because it kills performance.