It is present on every Planet and is always ready to trade resources with any city that has the means because the contracts it insists on always heavily favor it. In short, OmniCorp buys low and sells high.
Backed up by his empire and limitless resources, Don Madalff delights in signing contracts with cities that are very isolated or that have no‐one else to trade with. But don’t mistake him for a big‐hearted altruist, he’s completely unscrupulous. He simply takes advantage of this kind of situation to buy or sell goods at the best possible prices.
But that’s only a tiny part of his deceitfulness. What he likes best is putting whole cities in peril by organizing competitions or challenges with lucrative prizes.
There are many mayors – or should we say former mayors – out there who would love to see OmniCorp collapse and take Don Madalff with it.
It’s no accident that buildings owned by OmniCorp are surrounded with watchtowers and are more highly protected than prisons. Except that, in the OmniCorp mindset, captivity is what lies outside these enclosures…
Omnicorp's main purpose is to be a NPC trade partner, and so you can trade all tokens with it, even citizens. It sells resources for 80.0 cash per token and buys them for 35 per token. For selling purposes, use it freely to increase your budget. For buying, use it only as a last resort - if you have no proper cities that produce the resource you need.
Omnicorp has limits, after all - it has initially 9999 cash tokens available, and 99 tokens of every resource. This changes, of course, when you start trading with them - all resource you sell increase their supply, while decreasing their cash. It is possible that Omnicorp runs out of cash, so keep in mind that you can't sell them stuff indefinitely.
In the Planet Offer Omnicorp was to be a grand entity, representation of the 'masters' of the server universe. It was speculated that Monte Cristo would issue all challenges and special events through Omnicorp, but that was never confirmed (since not a single event was organised in the 6 months of the Planet Offer). In Single mode Omnicorp's importance was overwhelming - at the time there was no trading between your own cities, so you had to conduct all your transactions with Omnicorp and put up with their cutthroath prices. Needless to say, this raised an outcry amongst all who didn't want to participate in the Planet Offer.
Monte Cristo listened to the pleas of players and reduced Omnicorp's initial prices with the Christmass Pack, although that became an empty gesture couple of months later, when the game was turned into wholy Single player.
There are several mods that deal with Omnicorp's current limitations.