I've run into an issue that breaks my collisions. Here's my method: Gather Input Project Rectangle Check for intersection and ispassable Update The update method is built on object_position * seconds_passed * velocity * speed. Input changes velocity and is normalized if 1. This method works well with just one object comparison, however I pass a list or a for loop to the collision detector and velocity gets changed back to a non zero when the list hits an object that passes the test and the object can pass through. Any solutions would be much appreciated. Side note is there a more proper way to simulate movement?