Why does the little flower appear on the start screen of Undertale?

Xiaohua is the final boss in the game.

According to the official operation of the Undertale game, Xiaohua is the final boss in the game, and players need to defeat Xiaohua to pass the level.

Undertale is a role-playing story game, unofficially translated into Chinese as Undertale, and was released on Steam by TobyFox on September 15, 2015.