Hey, I got myself interested in OCC, cause it doesn't require insane micro like huge maps. At first, I lose badly thanks to numerous newbie mistake. But after lurking in forums and a lot trial, now I can win fairly easily in Immortal, will try Deity soon. Maybe it's time to give sth back to forum, in case anyone like to do OCC for warmonger. 
This guide is assume that you already try at least few OCC games. And this is only v.01 so I really appreciate feedback, comment about anything you find.
0. The main strategy: this is the reason why we do this and not do that:
- Doing OCC for war is really hard because you only got one city to do all the thing, it is quite rare to find time to build wonder, building and army. So what will we do? My main strategy is going SE, build a minimum defensive army until you got all wonder you need, all necessary building, and goes for an all-out war.
- SE means you need a lot of food in you BFC, so looking for food rich start, if you got marble, all the better.
- Play defensive war until PA. Whenever at war, do everything you can to bride your PA to war. Otherwise, you have to tech Military Tradition for DP pact, which is way too long.
The defensive war doesn't mean sit in your city. Attack them before they get to you BFC. The last thing you want is some coward AI camping in your nice forest. The best defense army is cats with elephuts. Give barrage promotion to cats if they have HA. Normally, 3 cats and 4 phuts will do, more if you got time. Early war is only 4-6 unit per SOD.
If you take care of diplomacy, hardly you will be attacked before cats. But in case you do get DOW before cats, axe and spear is good to sit in your city and hope for the best.
- The wonder we need: oracle, mids, TGL. Other wonders is nice, but not necessary. If you really want, try GS and GE wonder. And absolutely no GA wonder. I read somewhere that by going GA wonder will prevent AI culture victory. With warmonger game, they will never get that. GW is really nice to have if you got time to have it, with GW and defensive war, you get GG like hell.
- The national wonder: HE, obviously, try to do it as late as you can, we really don't want GA polluted. GT to remove happy cap and war weariness, as late as possible, and if possible, don't build it. Oxford Uni, obviously. NE, I hate GA but NE is a must, and ASAP. The fifth one is not so important. IW and Westpoint is quite overkill by the time I got them, NP is nice, but again, I rarely got time for it. So, toss a coin if you need to choose. I often go with IW, cause it's nice to 1 turn-cannon.
- Get a holy shine: Some guides said that money is not important but just because they don't know how to spend it. You need money to sweeten the tech trading, other wise, you have to trade 2 tech for 1. Choose the tech you want, put the tech you trade and ask AI "what could make this deal work", if 2 tech equally, they will ask for some money. Money can help you bride AI to war, the lowest I paid is 225 gold for khmer guy to go to war with Mana.
- If possible, don't convert your neibour, let them covert you. The hammer you spend on missionary should spend on wonder or military. But if you must, consider missionary is military unit, their job is to unsure your security.
- Get a PA by lib communism by going gunpowder-chemistry path. Right after PA, choose steel next (with the help of you PA, you will get steel in 1-3 turns). Conquer the world with mace/knight/cannon.
- Corporation: If everything goes fine, corp will be too late, other wise, Mining is a nice one. Cereal is only option for this land map.
1. The custom game start:
- Choose Gahni: PHI is no-brainer. SPI is more than switch civis, it is about diplomacy. And trust me, diplomacy is as important as war. There is no way that middle finger diplomacy gonna work in OCC.
- Option Permenent Ally on. This option helps you do conquest and domination faster and less hassle.
- Turn off time victory. I don't know why but in my game it is limited to 500 turn, marathon speed . And that is too little time to do anything. My fastest win is 1100AD, so no way I could manage before 1000AD.
- Ragging barb on: it's really fun to try this. A good option to learn about fog-busting.
- The map: I tried and inland sea is the best map for this, high sea level to reduce land mass. Good point of inland sea is you only need to take care of diplomacy for your 2 neighbors most of time, others can go to hell. Not to mention this kind of map gives you quite good amount resources.
- Choosing AI: 8 AI for small maps is a nice number. You may want to choose 4 of them is warmonger and 4 of them is peaceful ones. We don't want all AI are BFF to each other, do we?
- The perfect start: is the normal start with 2-3 food with 1-2 gold\gems, even though gold\gems is not needed, AND your neighbor is Brennus. Why Brenus, you ask? He is the BEST PA that you could find. He is really good at war, extremely easy to please and friendly, thanks to religion (he will get buddist most of time) and OR. You may gifted him Mono so both of you can be in OR asap.
- Do we need stone? In fact, I think marble is more important. If you do not have stone, try oracle metal casing and run engineer, with a bit of luck you will get GE to rush mids. Maybe some will say that is luck dependent, well, reroll that map until you got stone is more than luck dependent, I say.
I use tech rate as milestone so in case you need turn or time, just let me know so I can change it.
2. The early game, from start until you got alphabet:
- Poly --> 1 worker tech (ag, ah, fishing depend on resorces)--> priesthood, writing, alphabet.
- We need hindu, so poly is the first. Depend on your resources, AG or AH or Fishing next. Then priesthood - writing - alphabet. With beeline you will get to alphabet first, I always be the first. OK, with alphbet, careful do backfilling while checking if no one got priesthood, you can try oracle sth extreme like CS or feu, otherwise, COL or MC is good choice. Never trade priesthood away until you finish oracle. My last game I have to oracle Theo because all early religion is gone, and brennus got nothing.
- Worker or warrior first? Worker if you can time it right after you got AG, AH or you have some mine to do. Then warrior, your aim is level 4 warrior with woodsman III to unlock HE and make super medic later.
3. Defensive war - from alphabet to CS:
- If diplomacy look danger, oracle currency, because money helps you to buy peace.
- When backfill, don't get all the tech you can, get the tech you need, means bronze, the wheel and maybe some other worker tech.
- After backfill and oracle, go artist path and trade for Math to chop mids(if you got stone), TGL. Followed by Construction, and Horseback riding (if you got ivory). Followed by CS --> metal casing, machine. Don't goes engineering.
- It might not a good idea to go to Music. I rather take Currency after Literature, as I said money is good. And you can pay money for peace, around 50-100 gold, I think. Otherwise, you got to pay by tech.
- Do everything you can to your PA, even when he ask for monopoly tech. Keep your other neighbor at Please, if possible, Friendly. Check often to see if you neighbor got OP with anyone and don't provoke that person. Others can go to hell.
- City improvement: farm and mine, left 4-6 forest for health problems. Chop all forest outside your BFC and put road around your cap. You will need 1 worker at first and 3 worker after you got Bronze. 3 is good because most improvement is done in 6,9,12,15 turn. Group them and you will get less worker micro.
- City grow. I know it is tempting to run specialist ASAP, but in OCC, grow first. And run specialist when you about to hit happy/health cap.
- Keep your neighbor at Please at least. Focus to get 3 main wonders, infrastructure and an small defensive army. Be sure to share the war with your PA, you need at least 40 turn in share war. I often have 2 choice for my PA who is my 2 neighbor, when they go to war, I go too, but quite safe hiding in their back.
- If you can get around 150 beaker per turn, you will be fine.
4. Mid game - from CS to Communism:
- Goes lib way, with one turn to complete, then change to gunpowder path. Trade theo or philosophy for engineering, you will need a lot money for this trade.
- Time to focus lib Communism, some might said settle most of your GP, well, yes, all of them except GS. Because GS has highest bulb value, education on the way to lib, scientific method. I often burn 3 GS to Communism.
- Don't get scientific ASAP. Research Lib first until 1 turn to complete, then scientific cause of TGL.
- By this time, you should know who gonna be your PA, and do everything you need to do to help him expand, make him stronger, protect his city like yours.
- Aim for 200-250 beakers per turn in this step.
5. Late game - Communism -Steel:
- Congratulation, you're there. Now is time to nicely ask for PA, if you still not got enough share war, just bride them to attack anyone, anyone will do, share the war and check every turn to see if you meet the requirement. You can have PA when you are at war.
- The first tech after PA will be Steel. Chump out cannon/mace/knight and go after the neighbor of your PA. The aim for first war is making your PA stronger, bigger. Don't forget to bride your other neighbor go to war with someone else. You don't want to be back-stabbed.
- Now you can forget about your beakers, put every one out to work workshop. You will get 4-5 hammer per workshop (guild, chemistry, state property and caste system). Aim for 28-32-36-40 hammer in your capital. With Buro and HE, you can make cannon in 2-3 turns. Make about 5 cannon to help your defensive army goes to first offensive war.
- During first war, your job is to reduce defensive until 1 archer/longbow/cats in enemy territory and let your PA capture the city. Absorb all the land you could get, and don't settle for peace or vassal at this stage.
- One note, never, ever accept peace vassal. When you got PA, your PA will give ALL your tech to the vassal for free. And you know that peace vassal can break free at their will.
- After first war, regroup and plan for next step, vassal everyone, and fast. You will need around 8-10 cannon, 5-6 knight, 3-5 mace and most important, a super medic. I often make super medic from woodsman III warrior from barb day.Woodsman 3 and medic I will give you same result as medic III. Attack and raze all the city until they cave in and vassal.
- Don't rest after attack, you can rest during bombardment. Choose the whole group, press ctr-H to select wounded ones, let them rest while others do the bombardment. It might take 2-3 turn bombard so your group will have enough time to heal. Make sure you check who is still wounded every turn. You don't want healthy cannon to rest, do you?
- Who is the first? Normally, the closet to your army atm. I always feel bad if I have to go after my other neighbor, who I worked so hard to make Friendly. So, leave him out if he still Friendly with you, gifted him some tech, bride him to war to keep him off your back.
- Your city still make cannon and knight to supply the front. I often make them in 2 groups. 3 cannon and 2 knight to the front.
- After your first vassal, everyone will become your vassal after you take 1 or 2 city. That's show them who is the boss.
- Watch the globe turn red and know that you alone, single handed (with PA, ofc) dominated this hellish world.
Thank you for reading this guide, hope it will be some use to you. And again, I really appreciate feedback and comments, about anything.
This guide is assume that you already try at least few OCC games. And this is only v.01 so I really appreciate feedback, comment about anything you find.
0. The main strategy: this is the reason why we do this and not do that:
- Doing OCC for war is really hard because you only got one city to do all the thing, it is quite rare to find time to build wonder, building and army. So what will we do? My main strategy is going SE, build a minimum defensive army until you got all wonder you need, all necessary building, and goes for an all-out war.
- SE means you need a lot of food in you BFC, so looking for food rich start, if you got marble, all the better.
- Play defensive war until PA. Whenever at war, do everything you can to bride your PA to war. Otherwise, you have to tech Military Tradition for DP pact, which is way too long.
The defensive war doesn't mean sit in your city. Attack them before they get to you BFC. The last thing you want is some coward AI camping in your nice forest. The best defense army is cats with elephuts. Give barrage promotion to cats if they have HA. Normally, 3 cats and 4 phuts will do, more if you got time. Early war is only 4-6 unit per SOD.
If you take care of diplomacy, hardly you will be attacked before cats. But in case you do get DOW before cats, axe and spear is good to sit in your city and hope for the best.
- The wonder we need: oracle, mids, TGL. Other wonders is nice, but not necessary. If you really want, try GS and GE wonder. And absolutely no GA wonder. I read somewhere that by going GA wonder will prevent AI culture victory. With warmonger game, they will never get that. GW is really nice to have if you got time to have it, with GW and defensive war, you get GG like hell.
- The national wonder: HE, obviously, try to do it as late as you can, we really don't want GA polluted. GT to remove happy cap and war weariness, as late as possible, and if possible, don't build it. Oxford Uni, obviously. NE, I hate GA but NE is a must, and ASAP. The fifth one is not so important. IW and Westpoint is quite overkill by the time I got them, NP is nice, but again, I rarely got time for it. So, toss a coin if you need to choose. I often go with IW, cause it's nice to 1 turn-cannon.
- Get a holy shine: Some guides said that money is not important but just because they don't know how to spend it. You need money to sweeten the tech trading, other wise, you have to trade 2 tech for 1. Choose the tech you want, put the tech you trade and ask AI "what could make this deal work", if 2 tech equally, they will ask for some money. Money can help you bride AI to war, the lowest I paid is 225 gold for khmer guy to go to war with Mana.
- If possible, don't convert your neibour, let them covert you. The hammer you spend on missionary should spend on wonder or military. But if you must, consider missionary is military unit, their job is to unsure your security.
- Get a PA by lib communism by going gunpowder-chemistry path. Right after PA, choose steel next (with the help of you PA, you will get steel in 1-3 turns). Conquer the world with mace/knight/cannon.
- Corporation: If everything goes fine, corp will be too late, other wise, Mining is a nice one. Cereal is only option for this land map.
1. The custom game start:
- Choose Gahni: PHI is no-brainer. SPI is more than switch civis, it is about diplomacy. And trust me, diplomacy is as important as war. There is no way that middle finger diplomacy gonna work in OCC.
- Option Permenent Ally on. This option helps you do conquest and domination faster and less hassle.
- Turn off time victory. I don't know why but in my game it is limited to 500 turn, marathon speed . And that is too little time to do anything. My fastest win is 1100AD, so no way I could manage before 1000AD.
- Ragging barb on: it's really fun to try this. A good option to learn about fog-busting.
- The map: I tried and inland sea is the best map for this, high sea level to reduce land mass. Good point of inland sea is you only need to take care of diplomacy for your 2 neighbors most of time, others can go to hell. Not to mention this kind of map gives you quite good amount resources.
- Choosing AI: 8 AI for small maps is a nice number. You may want to choose 4 of them is warmonger and 4 of them is peaceful ones. We don't want all AI are BFF to each other, do we?
- The perfect start: is the normal start with 2-3 food with 1-2 gold\gems, even though gold\gems is not needed, AND your neighbor is Brennus. Why Brenus, you ask? He is the BEST PA that you could find. He is really good at war, extremely easy to please and friendly, thanks to religion (he will get buddist most of time) and OR. You may gifted him Mono so both of you can be in OR asap.
- Do we need stone? In fact, I think marble is more important. If you do not have stone, try oracle metal casing and run engineer, with a bit of luck you will get GE to rush mids. Maybe some will say that is luck dependent, well, reroll that map until you got stone is more than luck dependent, I say.
I use tech rate as milestone so in case you need turn or time, just let me know so I can change it.
2. The early game, from start until you got alphabet:
- Poly --> 1 worker tech (ag, ah, fishing depend on resorces)--> priesthood, writing, alphabet.
- We need hindu, so poly is the first. Depend on your resources, AG or AH or Fishing next. Then priesthood - writing - alphabet. With beeline you will get to alphabet first, I always be the first. OK, with alphbet, careful do backfilling while checking if no one got priesthood, you can try oracle sth extreme like CS or feu, otherwise, COL or MC is good choice. Never trade priesthood away until you finish oracle. My last game I have to oracle Theo because all early religion is gone, and brennus got nothing.
- Worker or warrior first? Worker if you can time it right after you got AG, AH or you have some mine to do. Then warrior, your aim is level 4 warrior with woodsman III to unlock HE and make super medic later.
3. Defensive war - from alphabet to CS:
- If diplomacy look danger, oracle currency, because money helps you to buy peace.
- When backfill, don't get all the tech you can, get the tech you need, means bronze, the wheel and maybe some other worker tech.
- After backfill and oracle, go artist path and trade for Math to chop mids(if you got stone), TGL. Followed by Construction, and Horseback riding (if you got ivory). Followed by CS --> metal casing, machine. Don't goes engineering.
- It might not a good idea to go to Music. I rather take Currency after Literature, as I said money is good. And you can pay money for peace, around 50-100 gold, I think. Otherwise, you got to pay by tech.
- Do everything you can to your PA, even when he ask for monopoly tech. Keep your other neighbor at Please, if possible, Friendly. Check often to see if you neighbor got OP with anyone and don't provoke that person. Others can go to hell.
- City improvement: farm and mine, left 4-6 forest for health problems. Chop all forest outside your BFC and put road around your cap. You will need 1 worker at first and 3 worker after you got Bronze. 3 is good because most improvement is done in 6,9,12,15 turn. Group them and you will get less worker micro.
- City grow. I know it is tempting to run specialist ASAP, but in OCC, grow first. And run specialist when you about to hit happy/health cap.
- Keep your neighbor at Please at least. Focus to get 3 main wonders, infrastructure and an small defensive army. Be sure to share the war with your PA, you need at least 40 turn in share war. I often have 2 choice for my PA who is my 2 neighbor, when they go to war, I go too, but quite safe hiding in their back.
- If you can get around 150 beaker per turn, you will be fine.
4. Mid game - from CS to Communism:
- Goes lib way, with one turn to complete, then change to gunpowder path. Trade theo or philosophy for engineering, you will need a lot money for this trade.
- Time to focus lib Communism, some might said settle most of your GP, well, yes, all of them except GS. Because GS has highest bulb value, education on the way to lib, scientific method. I often burn 3 GS to Communism.
- Don't get scientific ASAP. Research Lib first until 1 turn to complete, then scientific cause of TGL.
- By this time, you should know who gonna be your PA, and do everything you need to do to help him expand, make him stronger, protect his city like yours.
- Aim for 200-250 beakers per turn in this step.
5. Late game - Communism -Steel:
- Congratulation, you're there. Now is time to nicely ask for PA, if you still not got enough share war, just bride them to attack anyone, anyone will do, share the war and check every turn to see if you meet the requirement. You can have PA when you are at war.
- The first tech after PA will be Steel. Chump out cannon/mace/knight and go after the neighbor of your PA. The aim for first war is making your PA stronger, bigger. Don't forget to bride your other neighbor go to war with someone else. You don't want to be back-stabbed.
- Now you can forget about your beakers, put every one out to work workshop. You will get 4-5 hammer per workshop (guild, chemistry, state property and caste system). Aim for 28-32-36-40 hammer in your capital. With Buro and HE, you can make cannon in 2-3 turns. Make about 5 cannon to help your defensive army goes to first offensive war.
- During first war, your job is to reduce defensive until 1 archer/longbow/cats in enemy territory and let your PA capture the city. Absorb all the land you could get, and don't settle for peace or vassal at this stage.
- One note, never, ever accept peace vassal. When you got PA, your PA will give ALL your tech to the vassal for free. And you know that peace vassal can break free at their will.
- After first war, regroup and plan for next step, vassal everyone, and fast. You will need around 8-10 cannon, 5-6 knight, 3-5 mace and most important, a super medic. I often make super medic from woodsman III warrior from barb day.Woodsman 3 and medic I will give you same result as medic III. Attack and raze all the city until they cave in and vassal.
- Don't rest after attack, you can rest during bombardment. Choose the whole group, press ctr-H to select wounded ones, let them rest while others do the bombardment. It might take 2-3 turn bombard so your group will have enough time to heal. Make sure you check who is still wounded every turn. You don't want healthy cannon to rest, do you?
- Who is the first? Normally, the closet to your army atm. I always feel bad if I have to go after my other neighbor, who I worked so hard to make Friendly. So, leave him out if he still Friendly with you, gifted him some tech, bride him to war to keep him off your back.
- Your city still make cannon and knight to supply the front. I often make them in 2 groups. 3 cannon and 2 knight to the front.
- After your first vassal, everyone will become your vassal after you take 1 or 2 city. That's show them who is the boss.
- Watch the globe turn red and know that you alone, single handed (with PA, ofc) dominated this hellish world.
Thank you for reading this guide, hope it will be some use to you. And again, I really appreciate feedback and comments, about anything.
A settled rep prophet is a thousand times more valuable than wasting on a shrine in OCC. In fact, prophets are almost just as valuable in OCC for settling than GSs. I usually wind up with a few during the game due to stonehenge and oracle and amass gobs of cash throughout the game for trading. 
