I honestly can not wait for the full. It's really quite good.
The music and style, in fact, the overall feel of the game was a nostalgic blast to the past for me, back to the days of wolfenstien 3D lol.
I consider my computer to be on the lower end, and this game lagged up lots for me. I was able to deal with it, I just needed very precise timing.
In my short time playing it, only two things brought this game down:
1) I really, really hope you do not intend to stick with that menu design.
2) The trees took crazy long to blow away. Can you even blow them away? I gave up after 30 rounds with the machine gun.
A suggestion I would make would be to make it in smaller regions, i.e you start in a room, go down the corridor, blow up some stuff, get the key, proceed to the next room and it loads a little. I think it's not the graphics that lag up computers, but the fact that you have EVERYTHING playing at once, like too many processes running in the background.
All in all, I feel this will make into a great game, well done.