iO

About

In iO you control a spherical character that can expand or contract to alter speed and weight. Shrink to zip through tight spaces or inflate to crush obstacles and build momentum. Each level challenges you to balance these mechanics while navigating hazards and solving environmental puzzles. The goal is to reach the exit as efficiently as possible with optional speedrun challenges for perfect scores. The game stands out for its tight physics interactions and clever level design. Players appreciate how size-based mechanics create intuitive yet surprising solutions. With 50 levels spanning varied themes and a focus on precision timing, it offers steady progression without overwhelming complexity. A small but dedicated community still discusses optimal routes years after release.