It's really annoying. I have a sudoku game on my phone, works great but give it internet access and it's suddenly full of sketchy adverts.

If I'm playing it on my commute, it's usable with mobile data disabled for the app. But when the train stops in a station long enough to auto-connect to wifi, immediate full screen adverts :(

Then don’t use an ad supported app? I have one as supported app on my phone - Overcast. The developer created their own ad platform and serves topic based ads based on the podcast you are listening to right now. Ironically enough I started to pay for a subscription even though it didn’t give me any real benefit just to support him until he started having ads.

I’ve found a lot of useful podcasts from the ads.

I’m gonna be That Guy for a minute: if you enjoy using a Sudoku app, isn’t there one available on more acceptable terms, e.g. a single purchase or a IAP that removes the ads from this one? I’m not saying you have to pay like $3.99/week for a scam one, but more like pointing out that if you don’t like ads (as I also don’t) why not support the developers who believe in selling software to you for a few bucks rather than selling your annoyance to Google via Adsense?