Dead Rising 3

Introduction
There are 30 total side missions available to you in the normal Story Mode game, 6 of which have you battle Psychos (there is a 7th Psycho, but it's not a side mission), which bring their own achievements. To get the Sideswiped achievement, you need to complete 20 of them. In other words, you can skip 10 of them, something you might have to do if you're running out of time and want to finish Story Mode before the bomb drops. If you're going for a 100% completion on the game, you will need to do all 6 Psycho missions, meaning that you need to complete 14 remaining missions. If possible, you can do these side missions much faster if you pair up with an adequate partner online. See Mission Outline below for a list of missions by chapter, including mission-specific rewards.

Where Side Missions Come From
The side missions pop up as you progress through Story Mode, usually in the form of fetch quests (i.e. going and getting an item and bringing it back to an NPC), escorting someone somewhere (e.g. guarding a cook as you bring him to a kitchen), or mini-boss battles. They usually come about when you get an incoming call (press up on the D-pad to answer) from another survivor who tips you off about people in distress. Some missions unlock only when you complete earlier missions (see Mission Outline below).

Viewing Side Missions
You can view all current available missions by pressing the view button on your controller (the small button to the left of the menu button) and going to the Map (by pressing the left or right bumper buttons). The missions show up as blue diamonds on the map, and there is a list of missions to the lower-right of the map. When you are running around in the game world, there will be onscreen guides telling you the general direction and distance to get to the side mission (e.g. 345 meters away from your current location). You can also use the SmartGlass companion app to help you keep track of current missions. In it, go to the To Do list to see a list of missions. If you open up the 'map' section on Smartglass and then go to the map in the 'view menu' (in the game, not in SmartGlass) and select a mission from this list, the map on SmartGlass will automatically jump to the location of the side mission.

They are Timed
You have a certain amount of time to finish the quests before they disappear. You can see how much time is remaining by bringing up the map guide (view button on the controller) and looking at the mission list in the lower-right corner of the map. There will be a blue 'progress' bar that is counting down. Once it empties completely, the mission will be forfeited and you won't be able to play it again unless you restart the current game from the last save checkpoint or use chapter select later on to go back in time.

Also note that some side missions are much more time consuming than others (e.g., having to chauffeur NPCs around the entire city vs. simply collecting a few items in a nearby room). Once you activate a mission (i.e. by going and talking to the NPC), you can pull up the Map (menu button on the controller, left or right bumpers to scroll to it) and see where the mission's subtasks take you. If they're all over the map, feel free to not finish the mission (again, you can bail on 10 of them and still get the achievement) and do a less time consuming one instead. If you think you are running out of time in the main game, it's okay to forget about the side missions while you focus on finishing the game because after you beat the game you can use Chapter Select to go back and beat side missions you skipped.

Benefits of Side Missions
In addition to counting towards this achievement, completing side missions have several benefits: 1) they fill in the rest of the story of the Dead Rising 3 world, 2) they provide you with survivors (useful in other achievements) which you can then escort to safe houses, 3) they earn you various rewards such as prestige points, keys to other areas, and weapons blueprints.

DLC Side Missions Count
Our comrade SteampunkZomb1e has pointed out that DLC side missions also count towards the total, so those who purchased a Season Pass or individual DLC packs should have no trouble completing 20 side missions total.

Mission Outline
Here I provide a list of all missions, with information on what you get if you complete them (such as survivors or reward items). All missions provide PP points. Use this list to plan out which ones you can skip. I recommend not skipping those specially marked:
* need to complete to unlock subsequent missions
# weapons blueprints are in locked rooms only accessible if you do the mission
^ need to complete to finish certain PP trials
$ items needed to complete this mission

Ch 0
Signs of Safety (Survivor: Anna)
Garden of Peace [PSYCHO] (Items: key, weapon)

Ch 1
(none)

Ch 2
#$Craven Consultant (Survivor: Ravi; Item: blueprint [mini chainsaw]; Items needed: chainsaw, meat cleaver)
In the Cards (Survivor: Simon)
Darker Gods (Survivor: Christine)

Ch 3
Love thy Neighbor (Survivors: Matt, Elka)
*Time for a Hero (Survivor: Kenny)
Let's Blow this Town (Survivor: Hank)
Zombies Gone Wild (Survivor: Joey)
#Blood Barter (Survivors: Troy, Kent, Jesse)
A Question of Law (Survivor: Carrie)
^Lesser Evil (Survivors: Big D, Kandy)
All You Can Eat [PSYCHO] (Reward: key)

Ch 4
Family Style Dining (Survivor: Jason)
Speed Freak (Survivor: Derek; Reward: key)
*Under Armed (Survivor: Dwayne)
Dog Gone! (Survivor: Jorge; Reward: special food)
Play Time [PSYCHO] (Survivors: Eric, Julia; Item: weapon)

Ch 5
Kin and Comfort (Survivor: Kelsey)
Don't Look Now (Survivor: Kyla)
Will or Away (Survivors: Phil, Warren)
Contraband Conditions (Survivor: Marcus)
Fashion Victim (Survivor: Lena)
Eat the Rich (Survivor: Jose)
Look in the Mirror [PSYCHO] (Item: weapon)
Remotely Helpful [PSYCHO] (Reward: key)

Ch 6
The Hunted (Survivors: Doug, Lauren, Winnie)

Ch 7
#Memory Lane (Survivor: Meryl; Item: blueprint [Electric Chair])
Love's a Drag (Survivor: Adam)
Single White Male [PSYCHO] (Survivors: Kenny, Regina; Item: blueprint [Junk Ball] )

During Chapter 0 after arriving at your first Combo Garage you will receive a two way radio. On the other end of the line is someone named Jamie who will call you occasionally with side missions for you to investigate. All side missions start with a call from Jamie. They will either be psychopaths you must defeat or survivors that you need to help. Any mission target markers will be in the form of a blue diamond. All survivors with a * before their name are added to the bulletin board.

I will list each chronologically with some details pertaining to each mission.

Chapter 0
1. Meet *Anna at the motel in Ingleton for "Signs of Safety." She will ask you to get three cans of spray paint. They all have mission markers. You will receive 12,500 PP and get a tutorial on safe houses.
2. Go to the Zen Gardens for "Garden of Peace." Zhi is the first psychopath. Kill him to receive the "Wrathful" achievement, 20,000 PP, and the key to the Happy Good Mart which contains a Frank Statue.

Chapter 2
3. Go to the Bite the Bull restaurant for "Craven Consultant." You need to bring *Ravi a chainsaw and a meat cleaver. The chainsaw is in the hardware store on the East side of the map and the meat cleaver is upstairs in the kitchen. You receive 10,000 PP, the Mini Chansaw, and the blueprint for it.
4. Find *Simon on the gun store roof for "In the Cards." All cards have mission markers. You receive 25,000 PP.
5. Find *Christine in the cemetery for "Darker Gods." All sigils are easily visible in the cemetery. When complete, you must melee her once (preferably without a weapon) for her to follow you. You receive 10,000 PP.

Chapter 3
6. "Love Thy Neighbor" is located in small rundown neighborhood in the Northeast of Ingleton. Elka needs guns and Matt needs food. Food is to the south in Big Bulls Quality Meats and the guns are in the gun store. You receive infinite spawning food and firearms and 20,000 PP.
7. "Time for a Hero" can be found in the construction yard in South Almuda. Do five jump kicks and make one combo weapon in front of Kenny. Receive 20,000 PP.
8. On the central bridge is "Let's Blow This Town." Hank needs three items. Two are to the East and one to the West. Return all items and receive 40,000 PP.
9. Go to the mansion in Sunset Hills for "Zombies Gone Wild." Lure three male zombies from outside the front door, into the room and receive 25,000 PP.
10. At the bus station in South Almuda is *Troy for "Blood Barter." Go to the strip club at the mission marker, and kill Kent in the white suit. Talk to *Jesse, pick up the locket, and return to Troy. There is a blueprint where you fight them. You receive 25,000 PP.
11. In the North of Central City near the safe house is *Carrie for "A Question of Law." Go get the briefcase at the mission marker and return to her. Receive 20,000 PP.
12. "Lesser Evil" is on the South bridge. Get a combo vehicle and go see "Big D." Go to his apartment and kill him. Receive *Kandy, Big D's unique weapon, unlock his apartment containing clothes and a Frank Statue, and get 25,000 PP.
13. Go to Uncle Billy's Buffet for the psychopath mission "All You Can Eat." kill the boss for the key to the buffet, 20,000 PP, and the "Gluttonous" achievement.

Chapter 4
14. Go to Sunset Hills for "Family Style Dining." Get sushi from the mansion next door and talk to Jason. You get 25,000 PP.
15. Go to Annie's Old Fashioned XXX Supply in South Almuda for the psychopath mission "Play Time." Kill the boss and get his weapon, 25,000 PP, the "Lusty" achievement, and untie survivors *Eric and *Julia.
16. In the alley behind the barber shop in Ingleton find Derek. Beat him in a footrace and get 25,000 PP and Derek unlocks a gun store.

Note: I unlocked the achievement at this point, 4 shy of the 20 required.

17. Find *Jorge for "Dog Gone" in South Almuda. Take him, in the nearby van, to the restaurant at the mission marker. Once he make the hot dog, you get the infinitely spawning Master Dog, and 40,000 PP.
18. Go to the police station in Central City for "Under Armed." *Dwayne will need a pistol, riot gear, a grenade, and a shotgun. Riot gear and pistol can be found in the jail area of the same building. The grenade and shotgun can be taken from the nearby safehouse. After you bring all these items, you get 40,000 PP.

Chapter 5
19. Find *Kelsey on a roof in Ingleton for "Kin & Comfort." Drive her to a house in Sunset Hills. Receive 25,000 PP.
20. Go to the marker for the Psychopath mission "Look in the Mirror." Kill the boss, and receive 30,000 PP and the "Prideful" achievement.
21. In Central City find Kyla for "Don't Look Now." Go to the mission markers, destroy the trash bags and pick up the documents. Return to Kyla and receive 25,000 PP.
22. "Will or Away" is in Sunset Hills. Go there and talk to Phil. Head inside to find *Warren. Come back out and complete the mission for 25,000 PP.
23. Go to *Marcus on the central bridge for "Contraband Conditions." Destroy the five marked vans. Return to Marcus for 25,000 PP.
24. Go to Central City for "Fashion Victim." Take *Lena to three different stores. After that, take her to the store in the hotel for shoes. This unlocks a room with a lot of clothes to collect and 40,000 PP.
25. Go to the safe house in Central City for "Eat the Rich." *Jose wants five "hunks of meat." Get them from the safe house or throw the nearby dynamite into the zombies below. After he gets his zombie hands, you get 20,000 PP.
26. Go to the Mayor's mansion for "Remotely Helpful." Try to go downstairs, then destroy the security panels, then go downstairs. This gives you the armory key, 40,000 PP, and the "Slothful" achievement.

Chapter 6
27. For the side mission, "The Hunted," go to the markers for *Doug, *Lauren, and *Winnie successively and kill the three Spec Ops soldiers at each one. You get 15,000 PP for each survivor.

Chapter 7
28. In Central City is "Memory Lane." Take Meryl to the successive markers ending at her home and unlocking the location of a blueprint. You earn 40,000 PP.
29. Back in Central City is *Adam and "Love's a Drag." Use a Z.A.R. to destroy each of the speakers, all reachable from the stage. You get 25,000 PP.
30. Also in Central City is "Single White Male." On the yacht is *Kenny from "Time for a Hero." Go there and fight him, then kill all of the zombies on the deck and untie *Regina. Get the previously inaccessible Tragic Ending and earn 40,000 PP.