Open world, as in no loading screens between landscapes, is something we've thought about for a while, however we are a small team with limited resources. Certain designs with couch co-op would be difficult in a full open world & many of our designs already rely on the scene-to-scene approach.
The game will be open world in the sense that you will be free to travel, but with separated areas & loading screens between them. We don't plan on keeping the warp pads as the primary way to travel. You'll have to discover the entrances to travel between different areas.