Unlike in [[3-D WorldRunner]], in which the player can slow down or speed up the character using up and down buttons on the controller's directional pad, Jack's movement in ''JJ'' is set at a constant rate. When fighting world bosses (end of stage challenges), however, the player is capable of moving Jack freely in all directions.
Jack's basic actions consist of jumping and firing a gun. Jumping is essential to leap over canyons and is also useful for dodging enemies. Upon jumping, however, from lift-off till landing, Jack is completely defenseless, because he cannot fire his weapon while jumping. The distance of Jack's jump depends on how long the player holds the A button. In addition to jumping, Jack can also fire his gun to destroy enemies, provided that the player has obtained one. By the time the player reaches the boss at the end of any level, Jack is armed with a gun regardless of whether the player had picked one up earlier.
===Tasks, aids, and obstacles===
In each world, the player is free to travel in any forward-moving direction. The worlds are filled with enemies that attack Jack or block his progress, but also contain items that are either helpful or deadly to Jack; most of these items can be found in columns spread throughout each world. Canyons, which Jack must leap over, are also present in each world, and at the end of each world is a boss the player must defeat. None of the elements, items, or enemies in ''JJ'' are randomized; instead, they are defined in set locations.
All of the elements listed below appear in every world (the stopwatch, coils, and super-coils excepted), but not necessarily in every level:
; Canyons
: Canyons are present in each world, although the width and number of canyons differs greatly.
; Bosses
: Bosses appear at the end of every level and must be defeated to advance. The number of incarnations of a given boss increases from world to world. In World 1, for example, the player must defeat one boss, but by the eighth and final world, the player must face no less than six incarnations of the same boss.
; Enemies
: Each world has different enemies, but three types are consistent throughout each world: eyeballs, fireballs, and fire pillars. World 2 introduces the indestructible cell cluster, a new type of enemy that doesn't hurt Jack, but attempts to block his progress by shadowing his movements. As the player advances, the enemies of each world are progressively more difficult.
; Columns
: Columns litter every world, and are important as they house items that benefit Jack's progress (with the exception of the eye, which is lethal). Items in columns are obtained by crashing into them.
:* Shield boots: A pair of boots that grants the player invulnerability; Jack glows pink when shielded. Once Jack is struck, however, the shield is lost. The shield also vanishes upon reaching a boss fight, so Jack is unable to sustain any hits when fighting the boss. If secondary shield boots are collected, the player scores 500 points per pair.
:* Gun: When armed with a gun, Jack can shoot fireballs. Secondary guns score 500 points per gun.
:* Eye: When touched, the eye spells instant death for Jack, and is not defended against by a shield.
:* Extra life: Increases the "Play" count by one.
:* Invincibility: Similar to the star in ''[[Super Mario Bros.]]'', under invincibility the music shifts and Jack flashes alternating colors, and it only lasts for a short period of time. Invincibility protects Jack from the Eye, but doesn't prevent Jack from falling into canyons. When invincible, Jack can destroy enemies by running into them.
:* Stopwatch: The stopwatch resets the time counter and appears in only a few of the eight worlds.
; Tanks
: Tanks refer to small items spread throughout each world that can be collected to increase the player's score count and tank count. When collected, each tank scores the player fifty points. The number of tanks accrues between each level, but upon completion of each world the tanks are factored into the score count, divided at 200 points apiece. The tank count also resets upon death or game over.
; Jetpacks
: Jetpacks are spread throughout each world, and in each world they are only located in a specific level. When Jack touches the jetpack, he is transported to a bonus level, denoted in each world as level B. Bonus levels are filled with tanks and columns with helpful items.
; Coils
: Coils first appear in World 3. When stepped on, coils send Jack high into the air, and are essential for crossing some canyons.
; Super coils
: Super coils are flattened in appearance, and serve the same purpose as coils, except they send Jack even higher into the air.
===Worlds===
In ''JJ'' there are eight worlds composed of two to four levels each. Every level acts as a checkpoint; if Jack dies in World 1, level 3, for example, he continues at the beginning of World 1-3. Completion of each level also resets the time counter. Additionally, each world has a bonus level, denoted as level B.
* World 1: World 1 has four levels.
* World 2: World 2 has three levels; there are two incarnations of the boss at the end of World 2. World 2 also marks the first appearance of cell clusters.
* World 3: World 3 has four levels, and is unique because it marks the first appearance of coils. Like in World 2, there are two incarnations of the boss.
* World 4: World 4 has four levels, and it introduces super coils. At the end of World 4 are three incarnations of the boss to fight.
* World 5: World 5 has three levels. Meteorites in this world pose as cell clusters, but the meteorites are actually harmful. There are four incarnations of the boss.
* World 6: World 6 has four levels. Like in the previous world, there are four incarnations of the boss.
* World 7: World 7 has three levels. Like in the previous world, there are four incarnations of the boss.
* World 8: World 8 has two levels. It's vital that the player acquires the stopwatch in this stage. The player must face six incarnations of the boss, and the boss blends in with the background.
==Graphics==
==Graphics==
Although the two games were released only months apart, ''JJ'' showcased many graphical improvements over its predecessor ''[[3-D WorldRunner]]''. The sprites have been overhauled, while more attention was paid to small details; when fighting bosses in ''JJ'', for example, Jack is shown with a jetpack. The world backdrops are also richer in detail.
Although the two games were released only months apart, ''JJ'' showcased many graphical improvements over its predecessor ''[[3-D WorldRunner]]''. The sprites have been overhauled, while more attention was paid to small details; when fighting bosses in ''JJ'', for example, Jack is shown with a jetpack. The world backdrops are also richer in detail.
JJ (ジェイ ジェイ,Jei Jei?) is an action game developed and published by Square for the Famicom in 1987. In English, it is sometimes referred to by its long form, Jumpin' Jack, or by its subtitle, Tobidase Daisakusen Part II. The game was only released in Japan.
The sequel to Tobidase Daisakusen (known in North America as 3-D WorldRunner), JJ is a typical scrolling shooter, but it incorporates a third-person view, where the camera angle is positioned behind the main character. As in the previous title, the main character Jack must travel through various worlds, armed with his laser cannon and jumping ability, to defeat the serpentbeasts who have overrun the planets.
JJ was the last game by Square to utilize the "3D mode" and 3D glasses, and was Square's last work before the inception of the popular Final Fantasy franchise. The soundtrack of JJ consists of eight tracks, and all of them are either remixed or reused from the game's prequel, 3-D WorldRunner. The game was scored by Nobuo Uematsu, and is Uematsu's 16th work of video game music composition.
Although the game was only released in Japan, it is entirely playable by non-Japanese speaking players. However, DvD Translations went ahead and released a translation patch which changes the title screen, and displays the ending text in English. The patch can be found here.
Although the two games were released only months apart, JJ showcased many graphical improvements over its predecessor 3-D WorldRunner. The sprites have been overhauled, while more attention was paid to small details; when fighting bosses in JJ, for example, Jack is shown with a jetpack. The world backdrops are also richer in detail.
Like 3-D WorldRunner, JJ supported a "3-D mode" where selecting the 3-D mode and wearing 3D glasses makes the game appear in three dimensions. The glasses used are different, however. It has been noted that "whereas the 3-D mode in 3-D WorldRunner only required red/blue 3D glasses, the 3-D mode in this game requires special 3-D glasses whose left and right lenses switch on and off for every scan of the TV to give a perfect 3-D effect. These glasses were released only in Japan as the Famicom 3D System. These glasses were similar in their operation to the Segascope glasses released for the Sega Master System.
