Make your way through large parties killing everybody without getting caught, all so you can get some sleep. The motive quickly sets the tone for how seriously this game takes itself.

The controls are simple (one-handed players rejoice), which is good because they're not configurable. The graphics are reminiscent of the first GTA--they get the point across and would probably be offensive if you could zoom in a little.

It's your basic stealth concept

Think of it like the guard sneaking level in Ocarina of Time but with the stabbing. Knife people if they're alone or if you can hit everybody in sight before they reach a phone (protip: you can only sprint for a few seconds, and you're no Usain Bolt). Or lay traps, fiddling with ovens, speakers, and gumball machines. "Oh, you mean they'll spill gumballs and people will trip on them?" No, they explode. Remember Goldeneye64, where the tables exploded when you shot them? Like that.

Discovered bodies cause partygoers to call the cops and if you're the first person they see after finding the body, they'll come straight for you. If you've got the right exits or items, you can escape them, but that's rare, so hide the bodies or make sure you're not the first one seen around them.

The stealth aspect is semi-realistic in that people don't automatically know you killed someone just because they found a corpse (looking at you, Bethesda), but I still don't have any solid clue how to tell when I'm within someone's line of vision. Sometimes I escape detection from a foot away, others I get spotted from across the map through a floor-- is this a party for champions of long distance looking at things*? Combine that, the competence of the cops, and how long it takes to start a level over, and I often find myself waiting for long periods of time until I know I've got one group isolated enough. It's a drag. It's a silly game and waiting around in a silly game seems like such a momentum killer.
The traps are fun: time them right and they can clear half the level or get you out of a jam. Often, though, they're not placed anywhere useful. My main beef was that so many levels contained the same trap: poison the punch in the club, poison the punch on the roof, poison the punch on the boat.

The levels are largely the same.

You learn the locations of the item traps (there are only a handful of items, and they're mostly one-time uses to escape the police), and the phones, then get to work doing the exact same thing you did last time. No new mechanics are introduced, no new strategies are needed. Eventually, the levels get harder but only via your character becoming weaker (when you become a lady instead of a gentleman, which I wouldn't think makes a difference when it comes to stabbing people in the neck) and the bystanders becoming less likely to leave you alone.

There's a bit of a cutscene happening between levels, but it's not terribly interesting, and the dialogue is a little absurd ("seeing the blood was like a sledgehammer using my stomach as a welcome mat" what?) but it moves the "story" along.

In addition to moving, stabbing, and using items, you can dance (if you want to), but I still haven't figured out why you might. It draws attention, and that's never the thing you want to do. People react to it, positively and negatively, but not in a way that affects gameplay. Either I'm missing something or the devs just didn't want to send a character into a club without letting him defend himself in dance battles**.

Assorted thoughts:

Wow, these paramedics DGAF
Oh damn, that repairman just broke the entrance I was using
I appreciate a game with a good victory dance
The repairman just disappeared down ... the toilet? Oh I see you, Mario, you exit-breaking bastard
I'm getting better at this but I'm not sure how
Wow, gumballs machines are super prevalent at fancy parties
I wish there were better mechanics for chain reactions

*not a thing. I looked it up
**there are no dance battles in this game