Haha I get it, when the first boss warps into another dimension after you defeat it, it's actually traveling through time. So at the end when one of it's limbs pops out of Sergei's mouth, that was it's destination. Inside his throat. Evidence of this is seen in flashback to the first boss right before the end of the end game animation.
Leveling up skills i've found, simply raises their number, nothing more. I tested and it turns out they do the same damage before and after they've been leveled up. However you can augment their damage with Int or Str ... For every point it raises the impact (dmg) of the kidou or hakudo ...
Shinigami, or Soul Reapers ... I would please like a mute button, if only the sound track for this game was higher quality. My ears are literally hurting right now because my speakers were on full and I heard the music D:
I think that what would be really cool is if you could have some sort of tournament thing with like traditional deathmatch dynamics but each of your soldiers would work together ... allowing you with this specific gamemode to work as a team with your Medic, Assassin, Commando and Tank, you being one of them. This would bring new possibilities with your loadout and such for example, you could choose kevlar vests for your medic killstreak and use the assassins full radar in unison to greatly improve teamwork and such. + If you agree.
Adding some more weapons ... enemies and some new blocks. Maybe instead of a light source you could add torches and actually make sense. Water ... keys doors for keys. Maybe even make some options for shops armors character customization. Add some in-game tools maybe. Like a pick axe? Treasure chests ... different types of weapons ... like bows, crossbows. Maybe some spells staffs? Heck it's a dungeon crawler ...
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Or Battle, Cagematch, try to catch a Bounty, fight a Boss, participate in the Battle Arena or the Armada Wars, do a Challenge or two...