TUMIKI Fighters is a freeware side-scrolling shooter where the player controls a toy-plane, attempting to destroy enemy toy ships as they advance from the right side of the screen. There are different levels and each level ends with a boss ship.
The ship itself is very vulnerable and only has one main weapon, but by destroying enemies ships their parts can be salvaged before they drop down the screen, and are added to the player's ship. These new parts act as shields against incoming bullets and attack the enemy with the weapon they initially used against the player's ship. The effect is cumulative, so a small ship can quickly become a huge gathering of lego-like boxes. The enemy tends to adapt to the ship's power, firing more bullets if the ships become large. There is no collision detection with the enemy ships, only with their bullets. Next to a key to shoot, there is another one to pull in the acquired parts. This is used when a large numbers of bullets is fired and the player wants to avoid them without damaging the parts.
The 3D graphics are in pastel colours, with large, minimalistic shapes. It later became the inspiration of the Wii game Blast Works: Build, Trade, Destroy where the original game can also be unlocked.