A yellow star on a black screen.
Tap it and it does one of six things, picked at random: it spins, it falls over, it turns every colour, it shrinks away and springs back, it swaps black for yellow, or it grows a face.
That is the whole app. It fills the screen, it has no buttons, no menus and no settings, and there is nothing to read before it works.
Free, with no ads and nothing to buy. It collects nothing and never contacts anything — there is no network code in it at all.