The Sentry Drone comes from a long line of failed prototypes. Billions of dollars were pumped into the development of the perfect scout. The first prototypes produced used to be as expensive as a tank and used to break down often. The second line were cheaper, however they had to be remote controlled by somebody within a hundred miles. The third and final version was cheaper, was capable of accomplishing its mission even without supervision and could operate for over a week without maintenance. Decades have passed, and the model we see today is a distant cousin of the first crude unmanned ground vehicles fielded after the turn of the millennium. The Rottweiler Sentry Drone has been a workhorse of the United States military since the Global War on Terror and has been given another systems upgrade to keep up with the times. Recent problems with manufacturing Sentry Drones in bulk have resulted in them no longer being able to stealth themselves.
The Sentry Drone is an excellent, cost efficient anti-infantry unit. It is an easily mass producible, moderately fast stealth detector. These attributes make them the perfect scout and detector units that can be quickly deployed in sufficient number to spot enemy positions and to foil any attempts at infiltration.
Like all drones, the Sentry Drone fits in a niche between infantry and vehicles, being more cost efficient and quicker to deploy than dedicated vehicles while being faster and better armored compared to infantry. It is also more resistant to hazards that would be fatal to infantry, such as being immune to biological hazards and microwave radiation, and having increased resistance to radiation and flame based weapons.
On the other hand, the Sentry Drone is more lightly armed and armored compared to dedicated manned vehicles. Also, unlike manned vehicles, it can not gain veterancy or deploy drones of its own. Its light armor can be reinforced by purchasing the Drone Armor upgrade, which increases its armor by 25%, making it better in direct fights. The Advanced Drone Warfare upgrade gives Sentry Drone the ability to auto repair.
Sentry drones lacks AA defense, is very weak vs armored vehicles, does little damage against buildings and is weak vs most base defenses.