The zombie apocalypse game, "Rebuild, " on Kongregate requires, for its last achievement, you to defeat the game on either the "Hard" or "Nightmare" settings, although it may be done on either map size. Getting that achievement is somewhat difficult.
I beat the game on Harder, playing on a 10x10 map - if you're just playing for the badge, there is no real point making it even more difficult by playing on a bigger map or the Nightmare difficulty setting - defeating the game in all the possible ways: by closing the evil portal, curing zombiism, drafting a constitution and reclaiming every square of the town. Once the evil portal in the graveyard is closed, though, the zombie hordes stop appearing which does make beating it the other ways substantially easier.
The following are my tips on how to do this and get that final achievement. A degree of luck will also be needed, as problems can be caused by random deaths that cannon be prevented.
The Starting Area
The starting area is one of the most important elements. If you get an area that you aren't happy with, don't be afraid to restart the game until you do get a good initial layout. For more of a challenge, you can always try completing the game from an unfavourable initial setup.
Ideally, you want the following buildings next to your first four squares, bordering them on a side and not diagonally. A Big Farm, as they produce more food than two normal Farms, even though the amount of space is the same, a Hospital, a Laboratory and a residential square - Apartments hold more people, but Trailer Parks and Suburbs will do. You can, of course, redevelop other buildings, or try to get them in the next layer of blocks, but each of these options takes time.
Initial Setup with the Recommended Buildings on the Border
Why do you Need These Particular Buildings?
At the higher difficulties, there is an increased likelihood of people dying from random illnesses every turn. If there isn't a Hospital bordering, and not diagonally, your starting four squares it can easily take up to two game weeks to get one. This is more than enough time to lose several people if your unlucky, and really important early people if you're really unlucky. It's always possible to convert a Church; however, this also takes time and those Churches are really essential for the permanent Happiness boost they offer.
In the same way as was mentioned with the Hospital, if you don't have a Laboratory next to your starting squares, you will again lose time scouting and capturing one. Although this won't mean people dying, it will be probably enough time to have completed one item of research. As with the Church, the same argument - time and the Bar will be needed - applies against converting a Bar into a Laboratory.
Big Farms produce more than double the food of the normal Farm, even though they take up the same amount of space. Additionally, you only need one reclaim mission to recapture them. At the higher levels, you aren't producing enough food to survive, and if you can't produce enough from farming, you will need to send Scavengers out on missions to get food. You are going to have to recruit to increase your population base, you will run out of food even faster and people will die of starvation, and you can't afford to lose people like that.
Your initial accommodation is only enough to house 12 people. If you plan to recruit, and this is something you must do, you will need more accommodation buildings to house more people and grow your population.
As well as capturing the suggested buildings, send out a recruitment party to get more people, although you may have to wait for more accommodation buildings before you can do more than one mission. Also use your Scavengers to scout out neighbouring squares
After you have captured a Laboratory, immediately start researching new technologies. As your food supplies will be erratic enough at the beginning, research Preservation so you don't lose desperately needed food from it going off. Then, research Zombie Vitals, to increase your effectiveness in combat, and Binoculars to improve your recruitment efforts.
After these three technologies have been successfully researched, continue safeguarding your food supply and generation with Pesticides and Fertilisers.
Once your initial Big Farm, Hospital, Laboratory and Accommodation buildings have been reclaimed, start expanding in one direction towards the map border. Once you reach the edge, the area you have in contact with infested squares decreases, as zombies can't attack from off the map, increasing your security and making defence easier.
The direction you choose to expand should be based on the buildings available in that direction. You need Farms and Big Farms for food, Police Stations and Malls to increase your fort's base defence, Churches and Bars to increase your base Happiness and residential buildings to increase the population you can house.
Once you have a direction picked, head for the map edge as straight as you can. Try and expand in a path approximately two squares wid, but if there's a useful building just off the path, it can be worth reclaiming it. Other buildings from those previously mentioned, except for backup Laboratories and Hospitals, are mostly not needed, as they require redeveloping to be of use.
Whilst You're Expanding, Keep Scouting and Recruiting
Continually scout blocks for resources, and recruit new people as you expand. Scavenge food if required.
After reaching the edge of the map you chose, you then want to expand towards a corner. If you lose buildings in the centre of the map, these can be sacrificed for now, unless they are your only Laboratory or Hospital. Your aim for now is to remove the zombie threat from two sides of your fort by capturing an entire corner.
Once you have the corner with all the buildings you need in it, convert any useless buildings captured along the way into useful ones, and prepare to expand across the map. There are a number of ways to win the game; pick one and devote resources towards this.
You will suffer from a lot of zombie assaults, particularly from zombie hordes, once you start your chose method for beating the game. If you destroy the evil portal, this takes a lot of troops, so ensure your fort is strong enough to withstand the loss of a lot of defenders.
Your Laboratory and Hospital are vital. Make sure you have at least one of each that have at least one building between them and the fort border. This will prevent you from losing a vital building from a successful zombie attack, and some attacks will succeed unless your risk is 0%.
When buildings are lost to attacks, weigh up whether you need it back straight away. Losing buildings such as Farms and Big Farms early in the game will more than likely cause too big a drop in your food supply if you have a large population from constant recruiting. If the lost building isn't particularly important, it may be an idea to not bother with immediate reclamation of the lost block, and use your forces somewhere else.
When performing research, always have at least two people conducting the research, even if the extra researchers aren't scientists. If you just have one researcher, and they die or desert through random events, such as attacks, murder, disease or suicide, all progress in the research will be lost.
If you have two or more Laboratories, you may be advised to reasearch more than one technology, especially if you have the people.
Always recruit and scout. You are going to take constant losses, so you need a constant influx of new recruits to replace them.
Improve your fort's base defence by capturing Police Stations, and capturing and fortifying Malls. This helps free up soldiers for expansion missions.
Build and capture Bars and Churches. On Harder and Nightmare, it's very difficult to keep Happiness up, even if you throw lots of parties. A higher base Happiness level helps substantially.
If you capture Schools, you can use them to train specialists quickly. Survivors who haven't got a current specialty can become trained in a job specialty simply by doing it though. Survivors can become Scientists by performing research, and Soldiers by defending the fort. These two skills are probably the easiest to learn, but others can also be learned by doing.
Watch your threat level. Make sure you have enough people assigned to defence to protect the fort. If someone isn't doing something else, it can be an idea to assign them to defence.
There's no guarantee of immediate success from following this strategy, you will still need some luck. Random events can cause problems by having required people die, and if your selected corner has no Malls or Police Station, all your defence will have to be handled by people, meaning they can't be used elsewhere. Still, after a few attempts using this strategy, after days of trying to beat the game, I was finally able to complete "Rebuild" on harder.