State of Decay: Year-One

As O for oVR stated you need to postpone the final mission in order to be able to play 10 sieges. However, after a few sieges it definitely WILL be very difficult not to get overrun during a siege, so preparation is key! Here are a few basic tips for your preparation that helped me to defend my base during every siege easily. Feel free to add and correct me in the comments, i'll update the list then. However, if you follow these tips it is nearly impossible to lose during a siege.

1. At the very beginning of the game do not follow the mission objective! At that point in the game you have 2 NPCs that can fight with you and the zombies are not as frequent and aggressive as later in the game. Check the police station for grenade launchers (see point 2 for details), search as many places as possible, collect materials (see point 7 for details) and built as many outposts as possible to keep the zombies under control (very important later in the game). Definitely take your time, search as much as you can. You can even put supplies in a car and park it closely to the base, bringing it in later. However, don't drive the fully-packed car TOO close to the base or the mission may end.

2. It's ALL about the grenade launchers! There are supposed the be like 5 or 6 grenade launchers in the game. You have one in your base-inventory right from the start, the others you need to find, which can be tricky. I found 2 grenade launchers in the police station in the east of the map, so definitely check this place out. There are also at least two weapon stores in the game (I don't remember the exact places, one is in the area where you find your very first survivor, kind of north-east there). However, I didn't find any launchers in the weapon stores, but one in a random camp site. So I had four grenade launchers in my game. Why do you need them? Give the grenade launchers to your NPCs, they have UNLIMITED AMMO with these things, making them invaluable during sieges! Important: Keep one grenade launcher always for yourself during a siege, sometimes the zombies break through and you need to do some cleanup ;)

3. Do not recruit any soldiers, stick with the ones you get. Because of point 2 and the fact that you never know where your soldiers will be (automatically!) positioned in your base during a siege. If you have too many soldiers you can maybe only give half of them a launcher. If you are unlucky, they stand in bad positions and won't be very helpful! The fewer soldiers you have, the higher the chance for getting good tactical positions.

4. Build an Ammunitions Shop for grenade launcher ammo. You need this for your own grenade launcher, the other NPCs have unlimited ammo, see point 2.

5. Build a Weapons Lab and constantly built flame fougasses! (Maybe you can build those in an Ammunitions Shop too? Can someone clarify?). Before a siege and if possible between the two waves place the flame fougasses in front of your base, I always used like 15-20 in total. This becomes more important in later sieges, not so much during the first ones.

6. There are two entrances at the east of your base, one can be blocked with a car. Do that. Zombies can't break through there any more, making your life easier.

7. Between the sieges you should focus on:
- finding all the grenade launchers you did not find in the beginning.
- finding materials: You should get enough supplies from heli-drops, but materials will always be scarce. Focus on collecting those, the rest is not that important.
- rescue civilians
- rescue story-related survivors

8. In your Ops Center you can give orders to your people. Always put it to "Thin the herd", forget the rest.

A Siege occurs approximately every 30 min so this achievement will take at least 5 hours of gameplay on a single save file in order to complete. It is not uncommon to be done with all the missions having completed only 6-7 missions so you will have to postpone completing the final mission until you complete all the Sieges.

My solution is a combination of two strategies listed by Cheese Touch and Jimbo LaFleur but expanded upon to make this achievement, and Lifeline in general a cake walk.

At the beginning of the game head straight to the base and rescue it BUT DO NOT rescue the first survivor, Dr. Thomas Horn.

You still have two companions, no hordes, no sieges, and get full access to your base. You also don't save, so keep that in mind but it shouldn't be an issue.

Then take the next several hours and loot the entire map, saving the section with the first survivor until last. Your character will get tired but just drink energy drinks or coffee and use trucker pills to counter it. There should be enough available on the map to not require the medical lab to manufacture potent stims. Once the entire map is clear you will have approximately 8 grenade launchers in total, along with full food, materials, and a high level of fuel and medicine. The police station and delivery trucks on the highway for me were the most common areas to find grenade launchers, but I am sure there is a bit of randomness to it.

Anyway, once the map is swept clean and your base fully built and stocked, outposts built on your favorite support sites ect, go and finally rescue the first guy. The first siege is the only one you actually have to try on but it is only one wave so its easy.

After the first siege, most everyone in your base becomes playable, so now you can finally give everyone a grenade launcher. Because AI characters have infinite ammo with no friendly fire, there's no worrying about ammo. The AI seems just as effective with the 6 barrel and the single shot grenade launchers because of how they reload after every shot regardless.

Finally give Hawkes a break after being up for 8 game days straight on trucker pills and pick another character to level up.

Since everything has been salvaged prior, you now have ample time to rescue civilians and do other side missions. Once you rescue two or three soldiers (8-10 population) the game stops those missions and since nobody should ever die, that's one less thing to worry about.

If you want to make it even more unfair, wedge two vehicles across the breaks in the walls around your base, the places with the yellow poles, so zombies have more to get stuck on while they wait to explode.

Ammunition as a base resource will be extremely limited so simply call in ammo supply drops so you can keep refilling the mines around your base between sieges. You should get enough influence from the missions between sieges to get 1 - 2 supply drops each round. You can also do the long range drop but the guns that come with it aren't really worth twice the influence cost, and you'll just wind up over stocked with other resources.

Eventually the sieges might require you to do something, so I keep Hawkes at base as my "siege specialist". She is loaded up with ammo, grenades, molotovs, a scoped rifle, ect. When it gets to threat level two, I return to base as whatever character I was using, grab their grenade launcher and switch to my specialist.

Finally, as stated in previous solutions, do not do the final mission, just let the game keep running so sieges occur until you get to your tenth siege and achievement.

Any questions or comments please leave below or feel free to message me. Thx

My method for this is pretty simple and straightforward. Right from the start, do your best to get the "Focus Aim" skill on as many military as you can. Specialize in rifles or automatic weapons, and carry a weapon that holds the most ammo that you can find. You want to get "Focus Aim" for as many soldiers as possible in case anyone with the skill gets killed before you get the achievement.

When a siege happens, you can pretty much defend an entire base by yourself with Focus Aim (it slows down time allowing you to aim and allows you to get a headshot with every single bullet fired, preserving ammo). Prepare with 6 MREs to maintain focus any time you don't have enough stamina, and at least 3 meds just in case. Make sure your gun is loaded and carry at least 90 extra rounds. Also carry at least 3 Flame Fougasses or mines (the flames work best because there are residual flames for a short time that will burn extra zombies as they pass through it). You'll want to mine just to the left of the North gate (as you face out of the base), that's where most zombies try to come through, and another one to the left of the East gate (near the concrete barriers with the one yellow pole). Start mining when you hit threat level 2 or 3, before the actual siege. Also, park a truck in front of the SE gate, so Zombies can't get through. You can also bring some grenades to toss into groups of zombies.

Whenever one of your mines go off, and it's safe, plant another. Also make good use of the gas tanks that are set around the base, blow them up when there are maximum zombies around, or if you're getting overrun.

Stay inside the base, and wait for zombies to climb the fence, and take them out with focus aim. If an armored zombie starts climbing over, take out any regular zombies with focus aim, and then beat down the armored one. Be sure to focus on juggernauts or ferals, they are the only real threats.

I didn't use a single grenade launcher the entire time, the Focus Aim was more than enough to kill any Freak zombies that showed up, and pick off regular zombies, and it comes in extremely handy on missions as well. This allows you to do a more or less normal playthrough while guaranteeing that you can get the achievement.