poor design, good production
The bells and whistles are nice, but the game itself brings nothing new to the table. Okay, you can hit the zombie with your shield while blocking, so you basically can't lose. Okay, your weapon can be upgraded. Okay, you have amulets that may randomly do something marginally useful.
The fact is, there's no strategy to killing the same bland set of enemies over and over, much less to picking upgrades. I could accept this if the game was focused on action rather than strategy, but it's way, way too slow paced to be entertaining in that respect. The zombies are slow, the knight walks slow, he swings his sword slow (and kind of awkwardly), and he can't even jump high and far enough to avoid picking up an item.
You should redesign this game with more innovative ideas for enemies and more options for the player. Even more importantly, make the game more fast paced and make the character more dynamic. Keep the art, because that's pretty good.