Hard mode is unlockable game mode, which previously displayed "???" for player in title screen.
(which required player to beat this gamemode to see "true ending" )
However, in order to unlock it, you need to collecting all emblems in stages, and then a hidden passageway in the final stage "Hanging Gardens 2" will become accessible. Find and enter it will unlock "Hard Mode" (The game story will still continue from here.)

In hard mode, there're many significant change such as:

• Copen will be locked to level 1 (Has only 200 HP )
  
• Can no longer Heal with Lola's healing ability (But the checkpoint still provide player full heal)
  
• Far shorter invincible time after being hit.
  
• Cannot Upgrade
  
• Boss have different weaknesses, and can no longer be stunned.
  
• Boss have upgraded / empowered their attack.
  .
  AND
  .
  
• Has limited lives (Start with 2 extra-life. When all depleted and player die, player will be return back to ("Select stage screen") // Restart the stage from beginning).

However, there's possible way to get more extra-life which player can collect them in few location.

Extra-life location:
Can be found at second area, at a same spot where you find 4th emblem.

Extra-life location:
At the Hidden room in the first area, a same room where player collect 2nd emblem.

• Required : Gatling-Blitz

Extra-life location:
At second area of stage, one of passage room full with golden mines.
Destroy all golden mines. It will appear from the last one.
(a same one where player find and collect 3th emblem)

Extra-life Location:
In the first area, a same room where player find and collect 2nd emblem.
Activate the device in the first room with Doomsday Charge, then rush to the opposite room

• Required : Doomsday Charge

Extra-life Locations:
At the beginning of the second area.

• Required : Gatling Blitz

At second area, after pass second check point, same one where player find and collect 3th emblem.


At second area, before the gate to boss area, same one where player find and collect 4th emblem.

Space block, Ace stage has the most collectible extra-life and fastest, easiest way to collect.

Once player reach to the second area, hit the check point at very beginning.

Then you can start collect Extra-life you can find in this area





Be sure to avoid any "Checkpoint" at this point. Or you can restart the stage from very beginning.



Once you have collected all of them, go to pause menu, then choose "Escape" => "Retry"
(Be remind that it will consume 1 extra-life to process)


If player did correctly, player would be at beginning of second area, however
every extra-life player collected will respawned. and player can repeat the progress.




The game will stored your extra-life, although you quit the game. So enjoyed for Hugh amount supply of retry & extra-lifes



Once player are satisfied, to save the game, go to pause menu => escape => exit.
(Do not go to Option menu => Return to title screen, the game will not saved and you will lose progress!)

Are you afraid that you may lose all of your hard work collected extra-life, just for a single stage and then fail?
Well...there's way to prevent this case, it's very simple , "Copy your save slot"

This game allow you to copy / duplicate savefile which include your extra-life you have stored as well

This method will save you a big amount of time, in case If you lose all retry and don't want to farming extra-life all the way again.

As there's update 1.4.0, now my guide is become pointless, as people can simply go for assist mode for a free cheap infinite life and unlimited heal.

Seemed like they realized that "Hard mode" cannot be hard like what "megaman zero" or something used to be, they are now want this game to be easier than what this game already is, turning them from "normal mode" become "easy mode, and "hard mode" into "normal mode but still easy"
All player need is spam attack and heal, until you beat the boss.(and they are even grateful enough to give you "A" rank, after all healing abuse you have used in the game)
I hope they would do the same to the next gunvolt game, where player may don't even need to pay attention or learn about stage or the boss attack anymore

In conclusion :
Pros : now everyone, even newbie can beat the hard mode, without even need to practice. (best way to make player get achievement a lot easier) and it's optional feature.

Cons : It can ruin the entire experience or challenge of the game that meant to test player skill, mastered the game. Once you open assist mode in "hard mode", it will be not the same.