NG2 Game Mechanics

Controls

 * Press Left and Right to run
 * Press Up and Down while hanging from a wall to climb it
 * Press Down while on the ground to Crouch
 * Press A to Jump
 * Press B to Slash, damaging enemies, some projectiles, and breaking Item Orbs
 * Hold Up and Press B to use Ninjutsu
 * Press Start to Pause and skip cutscenes

General Mechanics and Parameters

 * Ryu has 16 HP, as do all bosses.
 * All of Ryu's attacks will deal 1 damage.
 * Slashing your sword has a 20 frame cooldown time, which forces you to stand still when on the ground.
 * Using Ninjutsu has a 20 frame cooldown time, and the projectile must be off the screen before firing again.
 * Ryu's HP is automatically refilled only after completing an entire act.
 * Ryu begins every act with the Shuriken and 10 Ninpo.
 * Ryu runs at 1.5 pixels per frame (at 60 fps).
 * Ryu climbs at 1 pixel per frame.
 * Ryu's collision box is horizontally smaller than in Ninja Gaiden, with respect to standing on surfaces.

Wall Climbing
Main article: Wall Climbing

Unlike Ninja Gaiden I, you can climb up and down most walls in Ninja Gaiden II as if they were ladders. After reaching the top of a cliff, however, you'll have to hold A and press left/right to scale to the top of it. Also, when you scale over the top of a cliff, you'll be travelling at "backwards mid-air" velocity until you actually land on top. If you slash in mid-air before moving backwards, you'll have full horizontal velocity already when you hit the ground. Thus, the fastest playthrough will have a Slash Climb at the top of every cliff.

Wall Clipping
Some walls in the game extend to the top of the screen, appearing unscalable. However, you can still get over the top of most of these walls by Slash Climbing at the very top, clipping you over the wall. It may take a couple of tries to get completely inside of the wall, though.

This is an invaluable time-saver in Stage 5-1 and in Stage 7-1.

Slash Climbing
Even though Ninja Gaiden II allows you to press up and down to easily climb a wall, you can speed up the rate of your climb by jumping off of the wall, slashing immediately, and then moving back against the wall. If done quickly enough, you can gain 2-3 pixels in height each time this is executed. Since you climb at a rate of 1 pixel per frame, each successful Slash Climb can save 2-3 frames. Done repeatedly throughout a run, several seconds can be saved. The technique can be difficult and tire your hands, though, so only do as much as you're capable of, as messing up can easily cause you to lose time.

Also note that this technique is especially fast in Stage 4-2 when climbing up waterfalls.

Damage Boosting
Main article: Damage Boost

Damage Boosting is very similiar to that in Ninja Gaiden I. However, there are some key differences: This means that you can get boosted at full speed, even in Stage 2-2 when the wind is active. Thus, damage boosting in Ninja Gaiden II can rarely slow you down, and is encouraged almost everywhere that you cannot easily pass enemies, provided that you have the health to do so. Keep in mind that if you have recently moved backwards in mid-air, getting boosted will move you at the same slow speed, too. While you can still reach higher platforms by damage boosting, it requires a bit more timing than in Ninja Gaiden I, since you usually have to hit an enemy at the pinnacle of your jump in order to get a successful increase in height.
 * You do not lose any horizontal speed when boosting. Whatever your previous horizontal speed was before the boost, that will be your speed during the boost.
 * You do not gain as much vertical height during a damage boost in comparison to Ninja Gaiden I.

Also keep in mind that you are invulnerable for about 1 second after taking damage. This invulnerability time only applies once you've hit the ground, so if you take damage from high in the air, you'll be invulnerable for longer.

Boost Grabbing
A Boost Grab is where you take damage from an enemy, and automatically grab a wall in mid-air during the resulting Damage Boost. In fact, you grab the wall the instant you take damage if you are close enough to it. This is similar to Wall Clipping in Ninja Gaiden I, except that you are required to take damage.

In Ninja Gaiden I and II, there are no ceilings - you simply pass through solid wall by entering it from underneath. Also, some walls in the background can be climbed, but if you're on the ground, you'll simply walk in front of it (or inside of it). If you're inside a wall and want to climb up its side, you typically have to move outside of the wall and then move back towards it so that it'll detect collision against it and you can begin climbing. You can actually grab onto the wall earlier and without pressing the D-Pad by simply taking damage while overlapping the side of the wall. You can be about 16 pixels from the edge of a wall and still cling to it after a Boost Grab. This is primarily useful in Stage 2-2, Stage 4-1, Stage 4-2, and Stage 7-1, saving significant time in most cases.

Air Control
When in the air, Ryu has full horizontal velocity in the direction that he is facing, but significantly lower velocity in the opposite direction. You can move at full speed in the opposite direction in mid-air if you slash before moving backwards. This is related to Slash Climbing, and is also directly applicable in Stage 6-1.

A sword slash lasts 20 Frames. Full horizontal speed is 1.5px/frame, and reverse mid-air horizontal speed is 0.5px/fr. Using proper air control, one slash would move you at 1.5px/fr for 20 frames instead of only the 0.5px/fr the entire time, moving you 30 pixels instead of 10 in the same time period. Thus, you'd save 20 pixels of walking, or about 13 frames with one sword-slash for air control, where applicable.

This can typically only be done on the first slash; to continue moving backwards at full speed in mid-air, you need to keep slashing on the first possible frame after the previous slash's cooldown.

Slash Jumping
Main article: Slash Jumping

Like in Ninja Gaiden, it is useful to slash jump to kill ground-based enemies without moving. However, in Ninja Gaiden II, the sword's hitbox is different such that it is often more difficult to successfully kill enemies with slash jumps. A and B must be hit in quicker succession than in Ninja Gaiden in order to kill most enemies. However, with a zero-time penalty from damage boosts in this game, it is often wiser to boost off of an enemy than kill it, or even to use ninjutsu to kill enemies at the expense of a few frames lost.

Landing Slash
Like Slash Jumping, performing a Landing Slash is slightly more difficult in Ninja Gaiden II due to a difference in hitboxes from the first game. Also remember that like the first game, landing on the ground cancels the cooldown of your current attack, allowing you to attack again immediately, similiar to Castlevania: Symphony of the Night.

Canceling
This refers to bypassing the cooldown of slashing your sword or using ninjutsu. Normally, you have to wait 20 frames from slashing your sword before being able to slash it again. A Landing Slash is one method of canceling, allowing 2 quick slashes in succession. You can also jump after slashing on the ground to cancel it, allowing another immediate slash in mid air. Combining these techniques together, you can slash 3 times in quick succession by doing a Landing Slash, a regular slash while on the ground, and a Jump Slash immediately afterwards. This can be abused to kill the boss of Act 1 in low% slightly faster, and in a Tool-Assisted Speedrun to kill some bosses nearly instantly.

Also note that if you jump immediately after using Ninjutsu, you can slash immediately (or use another ninjutsu, if the first shot has already left the screen) in mid-air.

Stage Hazards
Stage Hazards are game elements or objects (which aren't necessarily enemies) that increase the difficulty of platforming gameplay, often by modifying gameplay physics, or by directly dealing damage to or killing the player.
 * 2-2 Wind
 * 3-1 Darkness
 * 4-2 Waterfalls
 * 5-1 Spikes and Fire
 * 5-2 Ice
 * 6-1 Foreground