A Short Hike

From Wikipedia:

A Short Hike is an adventure video game by Canadian indie game designer Adam Robinson-Yu (also known as adamgryu). It is an open world exploration game in which the player is tasked with reaching the summit of a mountain to get cellphone reception. The game was released for Microsoft Windows, macOS, and Linux in July 2019, for Nintendo Switch in August 2020, and for PlayStation 4 and Xbox One in November 2021.