Small-space Sci-Fi Game

I was sitting in a meeting this morning, bored out of mind, so I pulled up Word and made a gridded battle area for a small sci-fi skirmish.

I used a 1" grid, colored in spaces for buildings, indicated doors and windows and threw on some wooded cover("explosions2" in Word). 

The final result was printed on a sheet of sand colored cardstock:

The scenario: Rescue the hostage from the enemy's clutches.

 The rules were made up quickly. Starting positions were determined by die roll:

Turns:
Roll 1d6 for initiative, high score moves first

Figures can move and fire each turn, with some exceptions(see further down)

Movement
Base rate of 4 squares, fast = 1d3 + base rate

Combat:

A close up of the good guys from the enemy's perspective

Ranges
pistols = 4 squares
smg = 6 squares
rifle = 10 squares. 

Short range = 1/2 of range or less.

To hit: 
short range/no cover = 4,5,6
short range/cover = 5,6
long range/no cover = 5/6
long range/cover = 6

smg's roll 2 dice to hit

Regulars save on a 6 on a 1d6

Characters roll 1d6 and consult the following table:
6 = Carry on
4,5 = Knocked down
2,3 = Unconscious
1 = Killed

On next activation: Unconscious becomes Knocked down, Knocked down becomes Carry on.

Unconscious and Knocked down can be auto-killed if enemy in adjacent square.

Other:
To shoot into a building through a window, if target figure is not in a square with a window, can only attack on (4-6 on a 1d6) and in LOS.
Doors can be kicked open on a 4-6 on a 1d6

If empty building (no figures on table) are there enemies in building?:

1 Yes (1d4 figures) and you can fire at them

2,3 Yes (1d4 figures) but they you can't fire this turn

4,5 No but that doesn't mean it's an empty building 

6 No and the building is actually empty

A close up of the other 2 good guys from my position.
They have bear butts. Get it? Bear butts?
 I think this joke says more about me than I'd like.

If a figure looks through a window into an empty building(no figures on table) do they see an enemy?
1 Yes (1d4 figures) and you can fire at them
2,3 Yes (1d4 figures) but you can't fire this turn
4,5 No but that doesn't mean it's an empty building 
6 No and the building is actually empty








Special rule for this scenario:
Characters can spend 1 turn searching a building - no other action may be taken

In the first building, a 6 means the hostage is there
In the 2nd building searched, hostage found on 5 or 6
In 3rd building searched, hostage found on 4-6
In 4th building searched, hostage found on 3-6.

With only four buildings, it does means it is possible hostage may not be in any building. Perhaps the intel was wrong or the hostage has been recently transferred to another location.

Added on the fly during my game:
Each turn, roll to see if a patrol enters the board 1-3 yes, 4-6 no. I used 1d4 figures for the patrol size. And rolled for which open edge square the patrol would enter from. Finally, I rolled to see which group of my players they would advance towards and at what rate (fast or regular).

I also used the Yes/YesAnd/NoBut/NoAnd method for questions about enemy tactics if I had any doubt.

The result: A fun game that ended in a TPK as wave after wave of enemy patrols finally took their course.