The game centers around a world created by Howard Steams, also known as the "1NS0MN1AC". Steams is an old sysop, seemingly mad, who creates the "Spiral Dominion," and populates it with bits of his memories and nightmares.
INSOMNIA employs an ANSI text interface. On the top level, you move between various map locations such as the "Shack Town Pub & Inn" or the "Sharded Tower." At this top level, the player can choose to enter a location. He might also face random encounters with NPCs, or find bits of puzzles to solve. Once the player enters a location, a smaller map appears on the right side of the screen. The player moves a smiley-face glyph around the map using W, A, S, and D keys, interacting with other characters, grabbing items, and taking other actions. The map interface is similar to Legend of the Red Dragon II as well as other ASCII or ANSI roguelike games.
The game features numerous puzzles, quests, and side-quests that must be resolved. Over time, the player may come to understand the riddle of Steams' madness.
Though a player can be killed by NPCs or other players, your character doesn't reset or "die" as is usually the case in other games. Instead, when a player's hit points drop below zero, the player moves to an alternate reality called "The Nightshade." In this zone, the player can battle strange creatures to regain hit points, or collect a unique currency called "nether." Once the number of hit points is positive again, the player re-emerges into the normal game world.
Unlike most BBS games, 1NS0MN1A is not turn-based, and multiple players can play together in real-time. Though a single player can complete the game alone, there are quests and locations such as various shrines, which require players to cooperate to unlock.
Achieving victory usually requires months of gameplay. Players who win the game become SysOps with elevated privileges that allow them to control aspects of the game, such as resetting the shrines, changing codes, or dropping loot boxes.
Like Jennings' previous games, INSOMNIA features dozens of small ANSI screens drawn by members of the art group Blocktronics.
INSOMNIA differs from typical BBS door games in a number of ways:
- It was created in 2020, about 25 years after the zenith of the BBSing scene.
- The game is not distributed as shareware or freeware for installation by sysops; instead, it is hosted on a single central server (bcrgames.com).
- The game's author, Shooter Jennings, was a celebrity when he wrote the game, famous for his work as a singer-songwriter.