Space aliens are infiltrating the U.S. from a sleepy little town on the Texas/Mexico border, snatching bodies and paving the way for a greater invasion. Those they abduct return as Pod People-like drones, normal in appearance until they reveal themselves. The government's response is you - a technician driving custom-built gun cameras mounted around the town. Similar to Night Trap or Double Switch, you must monitor the town for alien activity, and respond to protect the lives of the citizens and your agents.
The game is played entirely through four camera feeds from locations around the town. They mostly show loops of banal activity, but indicators will alert you when important action is occurring at that location. Switching to that camera will allow you to watch crucial plot clips, or defend that camera from aliens in a single-screen shooting gallery. As cameras take more damage, the picture from that feed degrades until the camera itself is destroyed.
The goal is pretty much to juggle between cameras so as not to miss an important plot point, while defending them from attackers or saving citizens from being abducted. In a neat twist, citizens who you failed to save may appear later as disguised aliens themselves.
As the game progresses, the invasion increases and becomes more violent, but the basic concept of switching between cameras and engaging in video shooting galleries remains unchanged.