Website implementing a couple of the classic decision support linear programming models. Not 20, and not 1. Maybe 2 or 3, with low enough barrier to enter somebody can do a "what if" over 3 or 4 unrelated criteria which need to arrive at a unified choice.

What's the app you'd build if you had ten years?

Something like we chat, a super app - one app to rule em all.

Why do people want that? The super app is called the OS and apps are supposed to be modules with single responsibilities, right? What’s the advantage (for the user) of one super app compared to multiple apps?

I think that's how it's usually described. The actual thing is too intricate to articulate and is a little bit different for everyone, so we just call it a super app. See also 'the holy grail of software engineering'.

Like a variation of some game....pong with powers and such. Or 3d tic tac toe, or or 3d connect 4. Something that start simple and by the time I know it, I am deep into it

Mine was an app that runs in the background and auto copies on select - ended up building it over a couple of weekends - pluks.app if you want to try it.

mine that is ai native static site generator with build in seo geo optimization