LOVED IT
Here's advice:
1. Make enemies come out faster and in greater numbers so the game is harder.
2. When you decide how the player can be killed, please dont make it possible to kill me with one shot. I want to have some kind of scale that'll show my health.
3. Add ambient music quietly in background, but make sure its not too loud.
4. Graphics and 3D are all good, dont do anything there. I like the feel of old style 3D.
5. Give the enemies some dying voices, but make sure that if the enemy is far away his voice is also far away and not in my ear.
6. When ther is a wall behind the attacker, you may add blood splash when he is shot. splash onto the wall that is.