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- This stage is an exclusive stage to the PC-Engine version of the game, and does not appear in the arcade, or any home conversions. However, it is interesting to note that a similar bone themed level was also added to the MSX and Commodore 64 versions of the game, although they are quite different in layout.
- The most obvious and unique feature of this stage are the giant skeletons that line the surface of the top and bottom terrains. They are completely passive and do nothing to attack you, but they can be deadly. Any time a weapon or missile strikes the bones of the gigantic rib cages, the bones fracture and fragment and fly out into space, turning the otherwise clear pathway into a moving obstacle course. There are two places of safety: the opposite terrain from where the bones line, or just below the height at which the bones fly out. At the opposite side, the bones are the most spread out and easier to fly through.
- The second new feature of this stage is the disembodied skulls of the great beasts whose carcasses line the floor. The bob up and down and fire beams of blue energy at you. The beams themselves are fairly slow and easy to avoid, but the skulls tend to fire them out in large numbers, creating narrow alleyways that you must fly between in order to survive. The skulls can take quite a bit of punishment before they are destroyed, but you shouldn't have too much trouble defeating them by the time they are half way across the screen.
- The skulls are usually positioned in such a way that they bob up and down through two thirds of the screen, while a narrow tunnel occupies the remaining third. Typically, you will find a red Dee-01 or two that will provide you with power-up capsules if you opt to take the smaller pathways and avoid the skulls. However, don't rush out to the other side of the corridor, as the skulls have the ability to about-face and fire back at you from behind. So even if you plan on taking the small pathways to collect the power-up, try to destroy the skulls before you do so that you are sure to be safe when you exit.
- Aside from the bones and skulls, there are an assortment of regular enemies to be concerned with as well, including hatches and a unique type of flying enemy. The enemies will typically fly from the right end of the screen to the left and off. However, if you hold your position on the screen, and they are given the chance, they will fly a certain distance immediately in front of you, stop, and begin flying backwards off to the right, firing continuously at you. You will probably be too busy firing constantly at enemies to notice them very much, but do be aware of the tendency to reverse direction.
- Among all of the enemies, there will also be a good stream of Ruguls. They will be both free flying and originating from hatches. The quicker you can destroy hatches, especially with your missiles, the fewer flying enemies you will have to deal with. Between the bullets fired at you by enemies, and the bone fragments, shields are a must for this stage.
- As you get closer to the end, you will notice a new type of terrain cannon. This cannon burrows beneath the sand until it is ready to rise up and fire again. When it does rise up and fire, it shoots a pod into space, generally in your direction. The pod floats out for a little while before exploding into a collection of three to five bullets that spray out in different directions. You can destroy the pod before it erupts, but it is even better to take out the cannons all together, especially once you reach the sub-boss fight.
- The sub-boss on this exclusive stage is simply a collection of floating skulls that typically attack two at a time, and bob up and down the entire height of the screen, slowly advancing on you as they do. In addition to destroying them and dodging the energy blasts that they fire at you, you will have to deal with a few of those cannons mentioned above. If possible, line yourself up to take the cannons out directly so that you have fewer threats to dodge, and can focus strictly on the skulls. The Big Core will arrive after you finish off the skulls.