Abadox (アバドックス, Abadokkusu) is a video game for the NES, subtitled The Deadly Inner War. It is a side-scrolling shoot 'em up in the vein of Gradius and R-Type. The game is notable for its unique visual design, as the game takes place inside the intestinal tract of a giant alien organism. Abadox is also difficult, since it takes one hit from an enemy projectile to be killed. In Abadox, if a player is killed, one must restart from a checkpoint passed before death.

The gameplay largely follows the conventions of side-scrolling shooters of the time. The player shoots down various enemies, all of which look like various internal organs (brains, eyes, and even cilia). The player can also pick weapons and powerups. Powerups include speed boosters, increased firepower, homing missiles, and shields similar to the "Option" featured in Gradius. For weapons, the player starts with the normal pea shooter, but can upgrade to a 3-way gun, a spread fire gun, a laser, and a hoop-like weapon. However, like most shooters, if the player is killed, all of the upgrades will be lost and the player will have to restart from the last checkpoint. In some cases, if the player dies, they may have to navigate through enemy fire with slow speed, which could prove more difficult than ever.

Another aspect of Abadox that sets the game off from other shooters is the second, fourth, and sixth stages. The play style changes from a side-scrolling perspective to a vertical one, but instead of scrolling upwards like a typical vertical shooter, the stage scrolls downward. The final stage involves an escape sequence where the player must navigate out of the alien's rectal cavity before the alien implodes. This falls in suit with another Konami game, Life Force, to which Abadox bears a striking resemblance.