Why does shooting while standing/running lock the controls for a moment? That is a level of unresponsiveness that actual NES games like Contra and Mega Man don't have, which singlehandedly takes your game from okay to unfair (and that's not even getting into the fact that you can't shoot while ducking)! If you're still willing to update the game, please make it so shooting doesn't prevent moving or jumping (and maybe make it so moving backwards in midair also instantly aims in that direction as well).
By the way, the exploding ceiling barrels near the start of 1-3 should be stationary because they always moved away when the enemy-spam showed up, meaning the only way to survive that part is to get lucky and hope the enemies don't shoot a ceiling of bullets + grenades when the barrels finally move back into position.
EDIT: The final boss is also badly designed because the gunfire forces the player to duck, preventing the player from being able to avoid the randomly-thrown grenades. It's also unintuitive how to kill the rocket launchers because the player's knife doesn't have its own button and only replaces the gun when close enough to an enemy.