On the Title Menu screen you need to actually press the Right Analog stick to proceed to the Main Menu.

You can browse through the menu with the Left Analog stick as well with the Dpad.

Confirming an action is done by pressing the A button
Cancelling an action or getting back is done by pressing the B button.

Not used buttons:

Left Trigger, Right Trigger, Back,

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start button - 180 char turn

Dpad - controls the character movement/navigation through the inventory

Left Analog stick - controls the character movement/navigation through the inventory
Pressing the Left Analog stick opens the game menu. pressing it again closes the game menu.(B button can be also used for closing the game menu)

Right Analog stick
by pressing it you open the character inventory, by pressing it again you close the character inventory.(B button can be also used for closing the game inventory)
Tilting it during a Lock-on cycles through enemies

A button - checks the environment/confirms actions
B button - hold down to absorb souls dropped from the enemy/cancels action
X button - attack, hold down for a charge attack(3 stages based on the weapon lvl), executes enemies that are downed
Y button - special attack (depletes weapon meter - limited use)

Right button/bumper/shoulder button - hold to lock on target(also charges the weapon for a charged attack)
- when holding down the RB button you can switch targets by tilting the Right Analog stick
- pressing this button together with a tilt to the side on the Left Analog stick performs an Evade

Left button/bumper/shoulder button - when hold down blocks attacks

Performing an long range attack(best for airborne enemies):

Samanosuke:

By holding down the RB button an pressing A button character shoots arrows(Limited to amount in inventory also needs to be equipped)

Jacques

By holding down the RB button an pressing A button character uses its whip to attack airborne enemies or regular enemies
(!!!this move is also needed for Jacques to move between vantage points e.g.: fireflies)

Onimusha mode: after collecting 5 purple souls press N on the keyboard. Yes on the keyboard, unfortunately the game does not recognize the Trigger buttons of the X360 controller and therefore its not mapped. So player is stuck with pressing the N button on the keyboard if he wants to activate the Onimusha mode.

Criticals:

Both characters:

Pressing the X button just before an enemy attack hits your character.

When pressing the LB button(performing a block) just before the impact of an enemy attack, player can perform a block critical by pressing the X button right after that.
(How the player knows the timing was perfect? The sound of the block will be high pitched and also the block effect will be bigger)

Performing an Evade(RB and tilting the Left Analog stick) just before an attack hits and pressing X button right after that

It is possible to "chain" criticals together right after executing any critical hit of the above type. When your critical hits the enemy and another enemy is attacking
you, at the end of your critical attack animation press the X button again to execute a chain critical. Like this you can insta kill 5-6 enemies that are attacking you.

Pushing the enemies away from the character:

Hold down the RB button and tilt the Left Analog stick away from the enemy then press X. This will perform a series of kicks that will move the
enemy away from your character, some characters can be downed by this action

Jacques

Oni Bind:

Holding down the RB button and pressing the X button performs an Oni Bind. Jacques will hold the enemy character with his whip.
(For stronger enemies it is necessary to charge the whip by holding the RB button longer or the Oni Bind will fail)

During the Oni Bind you can:

Oni Bind throw - press the X button again and tilt the Left Analog stick in a direction in which you want to throw an enemy.

Oni Bind attack - pressing down the X button multiple time in a succession will make Jacques shoot the enemy with his hand gun
- can be combined with the Oni Bind throw

Oni Bind special attack - press the Y button to release an attack through the whip to you enemy based on the element of your weapon(depletes weapon special meter)

This should cover the basic controls of the game and also some of its mechanics that are needed to master this awesome game.