I'm surprised no one's made a thread about this already.
Grief Syndrome is what is referred to as a Doujin Game, made by an official company but not technically affiliated with the creators of the series. Said company is known as Twilight Frontier or Tasfro, the makers of an awesome game called Higurashi Daybreak.
Grief Syndrome kind of reminds me of Metal Slug, only instead of shooting guns you have the five main zombies and their signature moves. It's kind of a button masher and can get both tedious and painful after a while, fighting hordes of familiars throughout stages based on the minimal amount of witch barriers in the series, until you get to the boss, which of course is the witch itself.
I kind of wish they had included some form of suspend gameplay feature, but apparently the point is to run through the entire game in one go, also known as a "lap" and with each lap the game gets progressively more difficult. I've never even bothered to play past the first lap.
After a while I ended up being only able to tolerate playing as Mami for some reason. She's said to be the most difficult character to use, and I see why. It's silly... a gun toting character who is a close range fighter. Seriously, her guns just release a small explosion in front of them. What the heck? And that special? Tiro FRICKIN GUN AS LONG AS THE ENTIRE SCREEN? Half the times you try to use that the enemy gets right ON the gun itself, so it doesn't get hurt at all.
And another thing, when you use a character's special move, your damage meter turns blue. If you get hurt even a tiny bit before that blue clears, you receive damage equivalent to the blue. So when Mami uses Tiro Finale, nearly her entire health meter turns blue. One little tap and... mumi why