Part of me objects to the very concept of expanding Hotline Miami - "IT IS A PURE AND PERFECT SHINING DIAMOND OF FLOW, CONTROL, MOOD AND BRUTALITY LEAVE IT ALONE" - but most of me just wants to play some more Hotline Miami. Devs Dennaton have quietly revealed that DLC for the game of fluid murder is in the works, as well as ongoing patching for the buggy old dear, proper joypad* support and more "secret" things.
This all came up from Dennaton's Dennis Wedin fielding queries on HLM's Steam community page. "If people enjoy the game and want more we have a storyline driven DLC in the plans with new characters and diving further in the story", he said, adding no less than three exclamation marks to the end of it. Perhaps this will provide the plot answers some feel they need, though I'm personally entirely happy with the story as is - it's about a Lynchian mood, not facts. I scoff at your facts, siree.
Also promised are "some things we are gonna do with HLM in a future update :) but that is a secret for now!"
Multiplayer? More masks? A face-biting attack?
More specific answers to specific tech problems may be found in this thread.
* I remember at, around age 14, ordering a "joypad" from Argos. The lady at the till had never heard of the term before, and regarded me with deep suspicion upon reading the word 'joypad.' To this day, I feel embarrassed that a stranger was convinced a schoolboy was buying a sex toy.