The most recent update for hit indie game Hotline Miami has enabled gamepad support. To use this feature, you will have to install the newest drivers for your Xbox controller, which you can find here.
Unfortunately, do disable gamepad support and go back to mouse and keyboard you'll need to first switch the controller to "off" in the options menu and restart your computer, otherwise "the game might run with a small but constant slowdown", the developer notes in the update on Steam.
Other features of the update include a bonus stage "Highball" which will be unlocked when you complete the main story. The update also increases the amount of randomly placed weapons, updates the pot of boiling water, adds more sound effects, and "slightly" modifies the first and second boss battles.