I have one-shotted the two most recent relatively complex apps I've tried:

1. a puzzle game with complex interplay, pieces to place, design vs. play mode, storing multiple solutions with the puzzle, and more. I've since iterated something like 200 times as I worked out the design etc., but the first iteration was 99% correct and what I asked for

2. a learn-to-read application with built-in stories (that the LLM wrote) the ability to import epub, text, and HTML, that uses the built-in speech libraries as a default, but also supports an open-source TTS library that I gave in the first prompt, tracks progress and problem workds, has multiple games to reinforce learning, and has a parental mode for tracking progress and configuring the tool overall.

Frankly I was stunned that Claude one-shotted that second app, there was a lot in the prompt, and it did it all. I fully expected to have to iterate on the first draft multiple times. But it worked out of the box.