Always Sometimes Monsters is a 2D top-down role-playing game. You control a failed writer for 30 days at the moment the rent is due with no money left and a publishing contract that does not go through as planned. At the same time a wedding invitation arrives from an ex the character broke up a year ago. Through a short sequence at a party prior to the events of the game, the main character (male or female) is selected from the guests there as well as the love interest (male or female) to tailor the game to the player's preferred gender, race and sexual preference.
The game starts in Dubtown, a city with shops, nightlife, working locations and many people to meet. The environment can be explored freely and there are many choices to influence the events. Money can be stolen, earned through work, or risked through gambling or investing in sandwiches. People often offer opportunities with ethical consequences. When out of money, you can attempt to sleep at someone's house or just on a mattress outside. There are various objects to collect and items can be bought or sold at shops.
The game offers a main narrative to follow, but the player is also offered different ways to approach it. Eventually, various endings can be reached, and there are also many premature endings after specific choices. In those cases, it is always possible to continue from a save point. The gameplay involves exploration, choice-making and interacting with characters through portraits.