Alien Soldier: Stages 8-9
6Stages 8 to 9 take place on a flying train. Epsilon-Eagle only travels a quick distance inside the train before the rest of the level takes him outside and on top of the train.
The first flying boss will turn invisible when its health is low.
The 2nd purple boss has a weakspot that's constantly moving around.
The 3rd boss is Xi-Tiger, the guy you see at the start of this stage who who overthrew Epsilon-Eagle from the Scarlet as mentioned in the opening.
He transforms into a Wolverine-clawed wolf monster to fight you as the last boss of this stage setting, figure out what weapon you can use to shoot at his chest: his weakspot.
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It appears that the Flame Force can be affected by different situations. In this case, the it follows the turbulence of the moving train to the left, during that time, it has less range when aimed at the right but more range when aimed at the left.