The scale of the different components appears to be different due to the way you shaded them. For example, the big gray blocks are far less detailed but larger-seeming than the building interior, which makes them not go together very well. The metal pipes outside are in a different style again--they're highly detailed whereas everything else is flat. The black background doesn't seem to fit at all. Also, your palettes. Pick one shadow color and have all of your color ramps tend towards that color. I like your sprites and blood smears, though, and the building interior goes together really well except for the wall. Try using a simpler texture for the wall and then trying to make all the other tiles in that style.

The Cocacola machine is great ^.^

Although I don't like the shading. Maybe make the shading on everything stretch out more?

 The outside of the building looks to have a different style than the inside. What's up with that? O_o

 Good :o

 try not to repeat the blood splats over maybe make a second or third variation. also maybe add some texture to the beams outside instead of making them completely round. same with the soda machine and the fire extinguisher over though very good.

 dangerous dave? :-)

 the white wall ruins the piece.

blood cannot be so high on the wall =) also small red dots on the white wall tile doesn't look good.

However I like those style alot - it's like 90's homemade games where graphics done by programmers =)

Cokecoala is

Nice work! I like the zombies' pose.