Here is an overview of the game, via Riot Forge:
CONV/RGENCE: A League of Legends Story is a single-player, action platformer game developed by Double Stallion Games and published by Riot Forge. Players will explore the spectacular world of Zaun as Ekko, a young inventor with an ingenious device to manipulate time. Follow Ekko’s journey, a fan-favorite League of Legends Champion, as he discovers that the power to change time comes with many consequences.
Watch the announcement trailer below. Visit the official website here.