Thunder Cross is a sci-fi side-scrolling shoot-'em-up developed and released by Konami for arcades in 1988.
Similar to the Gradius series, Thunder Cross puts players in one of two starfighters of the Space Force (the Blue Thunder 45 or the Red Thunder 24) as they battle mechanized alien hordes (Mechanikons) invading the colony planet Hanium IV. It features two-player simultaneous multiplayer and a power-up system similar to other Konami shoot-'em-ups (such as Life Force and A-Jax).
Three versions of the game were released, two in Japan and one worldwide. The worldwide version features numerous differences, changing the stage order, power-up system and control schemes. The game later received a sequel in 1991, titled Thunder Cross II.
While the game received no home ports at the time, it was later released for the PlayStation 2 in Japan on February 8, 2007 as the eighteenth entry in HAMSTER's Oretachi Gesen Zoku series. It was also digitally re-released as part of HAMSTER'S Arcade Archives series (featuring all three versions), once for the PlayStation 4 (exclusively in Japan) on June 8, 2017 and once for the Nintendo Switch (worldwide) on February 11, 2021. It was also included in the Arcade Classics Anniversary Collection compilation for the Xbox One, PlayStation 4, Nintendo Switch, and PC on April 2019.
Two main versions of the game were released: the original Japanese version and the later worldwide version. The Japanese version also received an updated re-release, increasing the game's difficulty.
- Both versions feature different stage orders for the first four stages. The 2nd, 1st, 4th, and 3rd stages of the Japanese version become the 1st, 2nd, 3rd, and 4th of the international version.
- In the Japanese version, Power Capsules cycle between different power-ups over time (with the exception of the first Capsule created after a life loss, which is always Option) in a specific order. In the international version, Power Capsules do not cycle and drop in a specific pattern (Vulcan if the player does not have it, followed by Option if the player has less than four, followed by Bonus).
- The international version has less power-ups, removing the Speed-Up power-up, the Boomerang Shot and Twin Laser weapon types, all three Super Weapons, and the hidden 1UP power-up. It also removes the weapon leveling system, using the maximum version once the Vulcan power-up is collected.
- The international version replaces the Super Weapon system with the "Lil' Baby", a screen-clearing bomb given from the start with limited use (3 shots per ship per stage). They can only be replenished by clearing the stage.
- The second button differs in both versions. The Japanese version use it as "Option Select", which changes how far apart the Options are vertically from the ship (instead firing Super Weapons once one is active). The international versions use it as "Bomb", which is only used for the Lil' Baby.
- In the international version, players start each life with two Options active. However, it also adds a recurring enemy that appears regularly if the player survives a certain amount of time. Intended to cut playtime for skilled players, this enemy explodes into a hail of bullets, as well as one larger bullet that homes onto the ship (requiring the use of Lil' Baby explosions to survive).