MAINLINE Launches on Steam as a Four-Second Roguelike FPS Inside the Bloodstream
The game's whole design hangs on a timer the player cannot see, which makes the no-gauge, heartbeat-and-darkening-vision feedback loop the actual product rather than a stylistic flourish.
Reporting from 1 source: Game Spark.
Indie developer Bakuebo released MAINLINE on Steam on September 14, 2026. The game casts the player as caffeine injected into the human body, with a four-second survival window inside the blood vessels that is restored by defeating enemies. Speed rises with each kill. Clearing a stage grants one of three upgrades, carried forward across six chapters that run from the peripheral veins to the brain. EX1, EX2, and an endless stage with Steam rankings are also included.
The six chapters run peripheral veins, heart, lungs, aorta, blood-brain barrier, brain, and the colors and scenery inside the vessels change as you move through them. Taking damage cuts the timer further, and consecutive kills intensify both speed and the on-screen effects. The speedometer reads in nanometers, since the setting is the inside of a human body rather than a road.
Upgrades to ammo capacity, firepower, rate of fire, and reloading carry over even if you switch weapons. The game is on PC via Steam at 300 yen, discounted to 255 yen through September 28. Bakuebo warns that both the game and its promotional video contain intense flashing effects.
Synthesized by Yomimono from the 1 cited source below, including Japanese-language reporting where cited, then editorially reviewed before publishing.