I did not find a thread for this game yet, and since I'm planning on making a TAS of it, I decided to make a thread.
I haven't actually completed the game yet, because the game is actually really difficult.
Mechanics
Leveling up
When you kill an enemy, you get XP ($8 in side scrolling stages and $18 in mazes). Once the XP value overflows from $FF to $00, you gain a level, which increases the damage your sword does. The top bar with the けん (sword) text displays your level.
Knockback cancel
For some reason you don't get knocked back by enemies while jumping (while crouching you get knocked back only few pixels). This may be useful when you can't get around an enemy faster and makes platforming over pits easier in casual plays.
Walking past enemies
Not sure if this can be counted as a glitch, but when an enemy in invulnerable after receiving damage, you can walk through him.
"Headshots"
In the 3D Maze encounters hitting the enemy's head does a lot more damage than hitting any other part of the enemy. Depending on the swing direction (vertical or diagonal) you need to stand in a certain spot in relation to where the enemy is. Even though you can jump, if the enemy is too high in the air, you can't hit it's head even though, you would be horizontally in a right spot while hitting him.
Glitches
Red Orb Glitch
The Red Orb kills any enemy in the 3D Mazes instantly, however using it outside a fight with enemy clears a portion of RAM ($04A8 - $04D7) making a "hole" in the maze allowing you to wrap around the map and overflow your coordinates higher than what you should have inside a maze. Exiting the maze with higher coordinates than intended leads to a wrong warp to other areas. Some areas are glitched up, since they were probably loaded from area that's not map data. The glitched up maps doesn't seem to have any uses. You're usually just stuck in them or you just crash the game. (See "3D Maze Layout" for more information on how the mazes work)
Blue Orb Glitch
Blue Orbs are used to kill all enemies on screen in the side scrolling stages. Using one on the first boss (the big flying one-eyed samurai head) kills him in one hit (intended?), however using it on the second boss (giant skeleton samurai with the spinning swords) makes the boss's swords lose their hitboxes making them harmless and beating the boss really easy. I don't know how this affects to the rest of the bosses in the game.
Sword Hitbox Glitch
Pausing the game on the side scrolling stages while your sword is out and changing to a projectile weapon (e.g. War Drum) causes your sword hitbox to not go away and stay in front of you damaging enemies that hit it.
Stage Skip Glitch
While in overworld, if you pause the game on the frame you land on the trigger, and then unpause while holding a direction (as long as it's not towards a wall) you can walk over the trigger. You need to do this twice to skip one stage since there are triggers on both sides of the gate.
3D Maze Layout
When you enter a 3D Maze it is loaded in RAM $0400 - $058F. Each byte has the tile type for two tiles. 16 bytes make one horizontal row making the maze 32 tiles wide.
The upper four bits gives the tile type for even tiles and the lower four for odd tiles.
The values in the four bits gives the following tiles:
0000 = $0 = Empty Tile
0001 = $1 = Solid Tile
0010 = $2 = Door Tile
0011 = $3 = Enemy Encounter Tile
0100 = $4 = NPC
0101 = $5 = Exit Tile (Overworld)
0110 = $6 = Item
0111 = $7 = Exit Tile (Stage)
1000 = $8 = Exit Tile (Bonus Stage)
Values higher that $8 give a glitched tile that has no purpose or use.
Enemy and NPC tiles activate when it's in front of you instead of when you step on it.
Door tiles are technically solid tiles. When you enter the door it skips you over one tile, since the door is not actually between the tiles.
The value for the enemy, item and NPC tiles that define it's type if stored somewhere else, however I don't know yet where.
This is all for now. By the way, there is also a TAS uploaded in Nico Video, which is reuploaded to YouTube, but there is a possibility it can be improved and there is no TAS of this game here yet. What category you would like to see?
-glitched
-no wrong warps ("breaking" the maze with the red orb is allowed as long as you don't wrap around the maze and leave it from the intended exit)
-glitchless
-damageless
You can suggest other categories too if I forgot one that's possible in this game.
