Comment by flohofwoe

I always point to the Metal-API debugger in Xcode for what I'd want a CPU debugger to look like, visualizing dependencies and dataflows with an actual graphical UI, letting me view data as something else than just hex dumps (e.g. as image or 3D mesh), etc... etc...

Of course the CPU side usually lacks semantics to automatically create data visualizations (while modern 3D APIs have enough context to figure out data dependencies and data formats), and that would be the "interesting" part to solve - e.g. how to tunnel richer debug information from the programming language to the debugger.

Also there's a middle ground of directly adding a realtime runtime debugging UI to applications via something like Dear Imgui (https://github.com/ocornut/imgui/) which is at least extremely popular in game development - and in this case it's trivial to provide the additional context since you basically develop the debugging system alongside the application.

PS: I'd also like a timeslider that "just works", e.g. travelling back to a previous state, taking snapshots and exploring different "state forks". And of course while at it, live editing / hot code reloading, so that there is no difference between development and debugging session, both merge into the same workflow.