Megapol
Megapol not only runs the city police force and prison service, it also manufactures vehicles, weapons and munitions. It directly competes with the Marsec corporation for lucrative markets in the mining colonies and Mega Primus. The major problems for Megapol are the criminal gangs that distribute Psiclone and the UFO incursions which are regarded as a threat to city security. Police vehicles bravely intercept UFOs as they materialize from the Dimensional Gates, but they are woefully under equipped to deal with them.
Benefits
Megapol runs the city's police, fire, and ambulance services, as well as producing some of the more important weapons and equipment in the game. They start out friendly to you, and you should keep them that way, because (not mentioning the fact that you absolutely need Megapol's weapons early on) Megapol officers are some of the most difficult enemies in the game. Megapol also has several road and air squad cars patrolling the city. It would be much more convenient for them to keep shooting at Aliens, rather than at you. If you become enemies with them, the most likely turn of events will end in you LOSING THE GAME.