Every single achievement, with descriptions, and guides to easily unlocking them under the cut!
Pretty self explanatory. If you're here, you likely already have this achievement.
"Play Party Hard 100 times"
Also pretty self explanatory.
If you do a complete playthrough of Party Hard, you should get this achievement pretty easily.
This one can also be easily obtained by simply playing through the game.
Same goes for this one as the last two.
"Pass level without traps 3 times"
If you just play three parties with John, you'll get this easily enough.
"Kill 10 people in a row"
These two aren't too hard to get, especially if you can use a smoke grenade or stun bomb.
This one can be a bit difficult. I recommend the Ca$ino party for this one. Avoid using the shortcuts or spare clothes in the beginning, as cops get harder to evade the more you successfully evade them.
"Complete all achievements"
"Lose level with 1 alive person"
I got this achievement on BBQ party, as it's the easiest party. I recommend beginning by playing normally, until you've killed all but two people. Be sure you don't forget the DJ. Once you get to that point, alert one of the people. The easiest way to do this is to carry a corpse to them. While they're calling the police, quickly kill the other person. You should get arrested, successfully unlocking this achievement.
"Kill all robbers in Casino level"
This one can be a bit difficult if you don't know the timing. If you walk in while the robbers are, well, robbing, they will all flee too quickly to be killed. The trick is to come in while they're fighting with the bouncer, then just kill everyone.
"Kill person who runs to call police 15 times"
This one is easy enough, you'll probably get it just playing the game. If not, Katie can be helpful for this achievement.
This can be a bit tedious. There are a few simple ways to get this achievement. First, you could kill yourself repeatedly with traps. For this method, I recommend the fire at the BBQ party, as it doesn't require someone to activate it. Horses also work, though most of them are RNG. Alternatively, you could play as "Hinter" and hold the sprint button until death.
Simple enough. Can be easily completed using shortcuts, or spare clothes. This achievement will likely be unlocked during a normal playthrough.
"Kill 15 people in a row"
The easiest way to do this is to use a smoke grenade in a crowd, then go wild. This achievement can also viably be obtained through the zombies at the miami party.
"Complete level without found body"
I find this achievement easiest to unlock on BBQ party, as there are a lot of huge blindspots. It's a bit tedious, but you can camp on the far right, by the dumpster. You can easily kill people in the side alley and those who wander into the right part of the house, and quickly dispose of their corpses.
"Get your ass kicked for dance"
This doesn't happen incredibly often, but it's not too hard to get, either. Just dance in large crowds until you get your ass kicked.
"Kill 50 stunned persons"
No particular tips for this one. Just use a stun grenade and go wild.
"Kill 50 persons with horse"
This one can be a bit difficult, due to RNG. However, if the horse spawns in BBQ party or campus party, it will be in a good position for kills.
"Complete level in 3 minutes"
This achievement is somewhat difficult to get in the base game. If you have the High Crimes DLC, though, this can be easily obtained. During the party, the timer will reset if you are killed during the boss. It isn't too difficult to kill him in under 3 minutes, I did it accidentally.
If you do not have the DLC, the bonus party with the eye monster can be quite helpful for this achievement.
"Kill 15 persons with one car"
This one is mostly just an achievement of opportunity. I recommend the biker party for this one.
This isn't too difficult to get, just poison food a lot. It's up to RNG whether it appears, but the food is very accessible in BBQ party.
"Complete level with FBI"
I recommend a party with a horse for this one, campus party in particular works well. Whether the zebra is there or not is up to RNG, so you may have to reload the party a few times. Begin by killing one person with the horse. Do not attempt to dispose of the body, or kill anyone else. Once a cop appears, they will try to cover the corpse. While they're doing this, kill them with the zebra. Wash, rinse, repeat. Once two cops have been killed, two FBI agents will appear. I recommend evading them at all costs, until they leave. You can also kill them with traps, if you please. Once you have done this, simply complete the level as normal, and you will unlock the achievement.
"Kill 30 people without alarm in one level"
You can just use the same guide for "Ninja" achievement as for with this one.
you do not have to complete a party in order to keep an achievement.
you cannot unlock any achievements through party bus.
you cannot unlock "Cunning" through underground sick.