At the moment, Corruption allows you to access secret dead ends and understand monsters' speech to some extent (25+ needed). As of last update, high levels of Corruption (40+) also prevents MC from showing affection in certain scenes (specifically in this last 2 updates, stops you from hugging mom and Amber) and make certain characters lose affection points (right now, Jake is the only one you lose point as far as i remember, if you have 6+ corruption BEFORE prison).