Hotline Miami is a violent top-down action game set in Miami, Florida in 1989. The protagonist is a hitman, nicknamed Jacket by the fans, who receives messages on his answering machine from mysterious employers. Most of the game consists of various missions that always start in the killer's own apartment. He receives a new task through his phone and then hops in his DeLorean to drive to the location and do the job. After each mission there is a short story sequence where he stops by a shop.
Missions are always set in buildings with one or more storeys. Jacket has to enter and kill everyone inside. This can either be done in a silent way, taking out opponents one by one, or as a hectic sequence where everyone is attacked at once. When alarmed, usually all opponents on a single level will be drawn to Jacket. There are various ways to approach opponents. Enemies can be taken out with melee weapons or guns. They can also be knocked out by punching them or slamming a door in their face, but they will get up. When they are only stunned, Jacket can perform a brutal finisher or pick them up to use them as a human shield. Enemies include regular guards but also dogs. Usually there is no starting weapon and they have to be taken from the environment or from opponents. Some of these are specific to the location, such as a boiling pot in a kitchen environment. Other melee weapons are baseball bats, knives, crowbars and more. Guns usually have a limited amount of ammo. When taking out enemies silently, the field of vision and sound need to be taken into account. In certain missions, Jacket can hang on ledges to move on the outside to another part of the building. He also has to take into account glass and transparent surfaces as enemies can see and shoot through them. All weapons can also be flung at opponents, usually just stunning them, but only one weapon can be carried at all times.
After each mission a rating is handed out based on various parameters. Gathered points unlock new weapons (which have a chance to appear randomly during a mission), and new masks are unlocked after each mission and can sometimes be found and picked up during missions. Before each mission Jacket can choose a mask to wear. It provides a perk such as a starting weapon, faster speed, doors that kill, friendly dogs and more. Both action and gameplay are brutal with lots of gore and blood. Often a mission needs to be tried multiple times as a single hit is fatal. In levels with multiple storeys, completing one acts as a checkpoint. Jacket has the ability to preview the environment, but only slightly beyond his position, not all of the map. There are also some boss battles against a single character.
Control is done through a gamepad or the combination of the mouse and the keyboard. There are separate actions for movement and Jacket can also aim in any direction. Actions include shooting, throwing a weapon and dropping it. He also has the ability to lock his aim onto a single character. Missions are unlocked one by one and the apartment always has small changes tied to the story. Sometimes there are longer cutscenes. Optionally players can collect letters hidden inside the environment. These open up the Puzzle section in a menu where the letters can be ordered into a phrase. Once complete, the phrase can be used in a later part of the game for a different ending. The game's soundtrack consists of a collection of electro and synthesizer artists, from eerie soundscapes to a booming rhythm.