Welcome to utopia.
The year is 2174, and you have been ordered to function as an orbital sniper. In your world there's just three kinds of people: VIPs, dissidents and normal citizens. VIPs run the world: they must not come to harm. Dissidents must die. If a commoner or two gets wasted in progress, it'll count against you when your post ends.
You were a normal citizen only moments ago. If you manage to prove yourself and keep VIPs safe in your area, they might make you a VIP. Or do poorly enough and they might decide that you're the enemy.
On screen, VIPs are designated blue, threats are designated red and the normal folk are white.
You control the target with mouse; right-drag or use mouse wheel to zoom. Different zoom modes are useful for different things. Zoom full out to see the whole situation at a glance (with all that useless clutter removed), or zoom full in for better aiming. Several levels of zoom in between give different information.
Left click fires your gun (which is based on some new physics laws that we haven't invented yet, as the target is destroyed instantly). The gun reloads for three seconds, so make sure you hit.
A typical game round lasts for about 4 minutes. It starts out easy, but gets rather nasty later on.
The houses that appear in the game's interface are taken from a satellite picture of Glasgow.