I know and use Maps.me a lot, but it lacks the survey character which I specifically find intriguing in this app. Also, there's http://www.pushpinosm.org/ http:

I know and use Maps.me a lot, but it lacks the survey character which I specifically find intriguing in this app. Also, there's http://www.pushpinosm.org/ http://www.pushpinosm.org/, but it will probably cease to function in iOS 11...