Hire some game devs that have worked on path finding in AAA games. They will find a way to partially pre process the map data in such a way that on-device computation can then let the user pick and choose what roads to favor and what roads to exclude.

And as an added bonus they’ll be unrelentingly optimizing your map application to the point where the UI will run at 144 Hz ;)

> Hire some game devs that have worked on path finding in AAA games.

I think you're seriously overestimating how many AAA games do any kind of fancy pathfinding beyond "just use A*".

Well. I’m not saying to unconditionally hire them.

Ask them a few questions in the interview to see what specific kind of problems they’ve been solving :)

Game routing is not remotely similar to real world routing. Neither in scale, nor in other aspects like road traffic or incorporation of human preferences.

In any case, I'm not suggesting it's impossible, just costlier than people imagine when they ask for the feature.

Cyclestreets already built a custom bike routing engine that is used in a bunch of different cycle map apps/websites, and has been for over a decade

https://www.cyclestreets.net/help/journey/routing/

at the most basic level it lets you choose between fastest and quietest routes, understands hills, cycle paths, etc.

There's many, many other choices https://wiki.openstreetmap.org/wiki/Routing

contraction hierarchies https://en.wikipedia.org/wiki/Contraction_hierarchies made cross-continent route planning practical and practically instant, eg in GraphHopper. A lot of the options listed there work offline.

Those overrides could be stored locally and the maps service could still return the same optimized graph. The client device can then swap out and override it and do the calculation on device.

> most users wouldn't want alternate routes

I wouldn't be so sure about that. I have seen many different users intentionally deviate from the suggested route because they know more than Google about what is best for them (or at least they think they do).

I sometimes I think Waze is sending me on an exploratory missions, giving me a sub-optimal route just to learn the current conditions along it.

s/users/queries/.

I wasn't saying this never happens. I myself deviated from Google Maps just yesterday. But, like, this was probably the only one out of my last 10 queries. And I was trying to say this is a minority of the queries.