Destroy All Humans! 2

One thing to note is that the last mission of Arkvoodle requires you to have collected 30 Alien Artifacts. This will require either venturing into Tunguska for one or more, or collecting all from Bay City, Albion, and Takoshima. Takoshima's last alien artifact requires Story Mission #15, but you can access it any time after that.

By completing all of the Arkvoodle Missions in Takoshima, you'll be given the Furotech Cell Detector, which will make all of the cells visible on your mini-map.