Grey Area is a series that debuted in 2000 AD, and features a scenario that readers may find similar to the District 9 movie – an alien ghetto on Earth.
In Grey Area, on one of the first instances being visited by aliens, humanity was “greeted”. Their technology, however, as based on tecnobacterias.
Thus, a good chunk of mankind got infected and suffered mutations from it, including hereditary ones. Because of that, all other contact with aliens should be limited.
This limitation comes in the shape of a designated landing spot on Earth – a walled city/spaceport where all aliens (xenos in the comic) must pass, be cleansed and verified. Above the clouds, a satellite array protects the approach from hostiles.
This walled city is called Grey Area, and was built in Arizona, deep into the desert. The local police force is called ETC, for “Exo Transfer Control”, and act as border patrol, investigators and standing army in the Grey Area.
They’re heavily armed, with full body armor, stun guns, laser weapons and such.
I think this comic would make for a great “Cops and Robbers” game. The ETC can bear all the tropes of an overstretched police force in a dangerous city, and the aliens offer an infinite amount of customization and campaign tailoring.
If you want to read more, 2000 AD website offers some (if not all) issues online.