If you knew anything about Sun Tzu and the time period - which was one of great conflict - you'd notice the book was meant for war. Of course, it helps in all walks of life as well.
If you rate it low give a suggestion? Don't just say it sucks or whatever...it's really annoying. And rating it what, 20, 40, 60% lower based on ONE LEVEL out of 10 easy levels, ten hard ones, and survival is ridiculous.
Fun but you don't get most upgrades by just playing through; grinding may be necessary. I found that maxing laser, then claw strength, and whatever from then on helps with the grind approach; the best grind level is 13, although 20-21 are okay. I think lightning is a must for the final snake boss.
Second boss was annoying but repeated tries gets him.
Try making him take damage from his own mines and bombs, and avoiding getting blasted off by his shoop.
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