Just made the 10k Colony achievement.
Use map 2, all the other maps will leave you food starved, space starved or power starved (map 3 is probably hardest because of that)
Mayors didn't really help, got 78 extra food from cottages, the others do nothing.
can be done in 120 days if you're focused easily, don't play 150 days, that's just an extra hour it will take you to finish.
First, start out as normal. Get one good housing district up, but then you don't make snipers - they're too slow and you don't need them. Get a few soldiers to clear the very few zombies that hang around - easy. 15 soldiers can handle a doom village on easiest level. Next, you rush Titans and set them to chase. This will clear the map very fast, you'll be hard pressed to throw up teslas behind them as they go to town. Tesla up the ENTIRE map and then make walls right next to the "no more building" limit. You will need all the space.
Ballista tower the entire wall - this should take up to 60 towers depending on your map.
Now look for the money food places where you can warehouse down those sweet +144 food advance farms.
Make as many farms, food cottages and warehouses until you reach total population + unspent food of 10k combined. This should be around 3k population and 7k unspent food. Do this first so you don't have to worry about food again, especially since advanced farms give +24 colonists.
I ended up with 61 advanced farms providing an average of 122 food each.
Now you quarry up all the stone and iron (not the gold), and get a lot of lumber mills down.
Place down the second and third housing district and make as many advanced mills as you can until you get uncomfortable with the remaining space. I have 102 advanced mills here. Now you throw down power plants instead of more mills to conserve space until you have around half the value of your spare food in power.
I made 17 power plants. You don't need stone anymore at this point, so use up your entire production if you want.
Now you spam cottages in every nook. Cottages, cottages and cottages. the reason for this is that 1. they require far less power per colonist (16 need 6 while a stone house needs 10) and 2. you nuked your stone production for the power plants. (This is also why you don't start this before you've walled up the entire border)
My final count is 308 stone houses in the housing districts and 466 cottages. Those cottages need 1400 power, if I had built stone houses instead as well, we'd be looking at 2300 power. Another 900 would be rough.
Now the final step is upgrading all your ballista to executors. Once you've finished that, you can go AFK until the game is won.
