亡
perish · die · lose · pass away
亡 carries a quiet weight: to be lost, to be no more. You see it in 死亡 (death, in the newspaper-formal sense), in 亡くなる (to pass away), in 亡命 (to flee one's country — literally "lose one's life as known"). The mini-game above puts 命 (life) on the screen and lets it fade. Tap before the fade is complete and you've saved it. Wait too long and 亡 surfaces in its place. Seven saves and the kanji is yours.
Common compounds: 死亡 (shibō, death), 亡命 (bōmei, exile, defection), 滅亡 (metsubō, downfall, ruin).