Ocean access is usually a key requirement for a decent OCC, particularly if you know you are on a small to medium sized island in a game with a lot of water. If you are on a large island/continent and know you have at least one neighbor, finding a high-trade site near them and setting up road/rail links with a large city can do away with the need for ocean access. I've done a few like that which came out fairly well. Once you get decent relations going you can trade maps often and look for the opportunity to bribe someone else's ship away.
Using Ocean tiles for an OCC can be done, but some key techs become critical. At the start you only get one food from an Ocean tile, but once you discover Seafaring and build a Harbor that goes up to two, which is enough to support one worker. Seafaring also brings Explorers, which are great hut-finders on large continents, and lowers the risk of Triremes being lost at sea. It is also on the tech path to Astronomy, which brings Copernicus and a big boost in research. Ocean tiles start with two trade each, and Republic and Colossus can double that to four without any Settler work building roads. The problem with Ocean tiles is lack of shields, so the other key tech I would mention for an OCC with a lot of Ocean is Engineering for King Richards. KRC gives you an extra shield on any tile being worked, even those that do not have one to begin with like Ocean. A city of size 12 working primarily Ocean can have a production of 12-15 and a huge amount of trade well before AD1, if you organize your research and avoid off-path techs. This works best if you have a couple offshore Whales or Fish to help things along.
There was a debate a while ago about Wheat versus Silk for an OCC; I personally prefer Silk for the extra trade, assuming I've got some Grass around to make up the food. Note that roading the Wheat before you mine it to Silk saves time and gets you an extra arrow, and RRing it later gets you an extra shield. To me there is no question that Buffalo is better than Pheasant, despite the drop in food - the extra shield and trade more than makes up for it, plus Plains can be double-irrigated to Farmland later. If I have spare time for my Engineers in the mid game I might consider changing the Coal to Wine, but it takes quite a while so I'd probably just stop at Buffalo. If you are not familiar with what you can transform terrain into, do some searching on Transform Terrain. I posted a chart a few years ago, but I don't remember the thread name.
As far as patterns go, the Randomize Resource setting just moves them around, but they keep their basic shape. To see what that is, start the Civ2Map program that is located in the same folder as Civ2.exe. Select a Normal map and look at the patterns of Whales and Fish (zoom out a little to get a better view, but not so much that the specials disappear). Now select Plains and draw a large continent over a few of the patterns. Each time you cover a Whale with Plains it becomes Wheat; each time you cover Fish it becomes Buffalo. The other thing to experiment with is the Resource Seed. Hit S and increment the number (usually defaults to 1 unless you Load a SAV or MP file). Every 16 the basic pattern will change; in between the pattern stays the same but shifts diagonally across the map. If you draw some Grass you will notice that it hides the specials, so when you play look for patterns that might indicate a hidden special under a Grass tile.
Diplomats&Spies and Caravans&Freights are very useful in OCC games because they do not take a shield to support them when you build them yourself. Popping huts too close to your city causes the units to be supported; popping huts closer to AI cities gets you unsupported units, and bribing Barb and AI units further away also gets unsupported units. Support is a bigger issue for an OCC game than a regular one. Sometimes early in the game (before Trade is discovered) the only thing I have to produce are Diplomats, so I may accumulate 4-6 of them.
Yes, it is true that Barbs cannot defeat even the weakest unit in a single city. There is some sort of multiplier in effect that makes your defense strength invincible. There seems to be a decreasing factor when you have 2-4 cities, and above that it is normal. Note that the AI can still take your city, so don't go defenseless. I've had a single camel defeat attacks by multiple Barb Archers and Legions. The problem though is that I cannot get the Barb Leader without a four-legged unit or a peninsula to trap him on. Note also that before you build your first city there is a much greater chance of getting a "mercenary unit" from a hut - something like 60%, and it will be unsupported too. Move around a bit to see if you can spot the patterns of specials and pop a hut or two before you settle. About the only thing I rue from that is when I get Warrior Code!
Ordinarily, it is impossible to transform Coal (the fish-hill special) into Wine (the whale-hill special).
