At the end of the game, after defeating the final boss (the Astronaut), you are tasked with inputting a code to stop a nuclear missile launch. You aren't really given much of a hint as to what the code could be, aside from a "special date" which references the very first scene of the game, a birthday party. The balloons in that scene were "1028" which I assume is for October 28th, his daughter's birthday. Why you would get balloons that signify the date and not her age, I have no idea, but here we are. Input that code to get this ending, the "good" ending.

At the end of the game, after defeating the final boss (the Astronaut), you are tasked with inputting a code to stop a nuclear missile launch. Input ANY other code aside from the correct one (1028) and you will get this ending, the "bad" ending.

This quest begins automatically as you are heading through the alley after Barbara joins the party. You will see a group of zombies standing next to a wall, and the game mentions you can just walk right by if you want. Obviously, we're going to challenge them for this achievement. The fight isn't too bad, just use your darts and rocks until a zombie gets close, then knock them back or hopefully kill them with your melee attack, as with any other encounter in the game. Don't be stingy on your bullets and serums, as this can be a tough fight if more than one gets in close at the same time.

After the fight, be sure to loot the sparkle on the ground to get the Baseball Bat.

To begin this quest, read the newspaper on the desk in the police chief's office in the police station, shortly after Chapter 8: Deliver the Supplies starts. You'll need to grab a key in this office to continue the story, so it's hard to miss. From there, rather than leaving the police station through the glass doors to continue the story, head back to the second floor to the room where you found Gordon's desk, and a huge blood smear on the floor going toward the right wall. You may have investigated this bookshelf earlier and it said you could hear something behind it, but you couldn't move it. Well, now you can move it and challenge the chief. There is a campfire in the room to replenish your HP, and you'll want to use all your best guns to take him down.

After leaving the mall and stopping at the gas station, you will be driving the car past a motel and get the option to investigate some gunshots. Make sure you choose to stop and check out the motel to begin this quest, otherwise you can miss it. Go to the motel lobby to get a key for Room 104, then inside that room you'll get two more keys and can head upstairs to face the boss.

This fight is extremely tough, especially on Nightmare difficulty. I used the shotgun with a small pushback with Ben, snipers with the girls, and a handgun with small pushback on Harry. This kept the boss from ever getting in melee range. You could maybe switch to a second shotgun with Harry to get more damage on the sister, and I'd probably use the sniper to take her down first if I did it a second time. Also take note that you need to heal constantly, I went through about 30 health items during this fight.

This quest begins automatically upon entering the Disco in Chapter 14. To complete this, you need to have a one on one fight with Ben against a Boxer zombie in the middle of the dance floor. This was much easier than I expected, to be honest. Use a handgun that fires three bullets at once, and heal each time you get hit. I think I only used about 8-10 health items in this fight and it was over in five or six rounds. Once the fight is over, grab the key from the balcony above the dance floor and leave the Disco to complete the quest.