Learn the Countries: interactive map and quiz
Learn all 195 countries of the world with an interactive map, a variety of games and a study list that keeps bringing back the ones you find hardest. No sign-up, built to work on phones.
Pace needs two or more snapshots. This launch has 1, so velocity and momentum read as unmeasured rather than zero.
A source that found nothing is a measurement. A source that has not run is a gap. Neither means the launch lacks the thing.