Oh this game is so fun xD I love combo games where you increase in power until everything is kaboom! Like many commenters, more grabbers from upgrades will be helpful. A way to order your grabbers what priority to get items might be useful too :P Lastly, maybe option to change background, or the background changes as you play the game could be fun too. And I LOVE the music :P Another idea I have is maybe upgrade your own bullet to be faster (just the one you shoot might be fairer), and for cosmetic, maybe changing the cannon and grabbers haha.
Maybe there should be a backstory of how Orcs, Undead, and Demons make an alliance? LOL. Usually one or the other is the final boss/area in most games lol
I beat the boss basically by having max defense upgrade and keeping the shield up. look for x4 all the time, recover health so you can take at least 100 dmg when you're not shielded. recover energy as needed. rage when there's nothing for you to do. Also, it's better to keep shield up so you don't take damage even if octopis attacks. with shield and counter on, you can take down the boss
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:D Thanks Tikikala!!