Hey people, this campaign uses the D20 modern rules, and is meant to use 4-6 players. There is NO magic is this game, but master-crafted objects obviously exist. This campaign has a military setting about 20 years into the future, during the third world war. Because of this, if you desire, you may incorporate some very low PL equipment from D20 future (I know I will), and maybe even a few cybernetics.
some recommended house rules are

1. Declare you roll, and roll in plain sight. You may be asked to re-roll, or if the GM thinks you are cheating the roll is considered a natural one.

2. Do NOT state your intentions out of character. In the real world combat is a messy and confused situation especially for a squad that is not prepared. You must speak in first person, which may allow the enemy to discern your motive before you take action.

Have a look at the wiki, it contains information that you will need to know about the game. wiki. There is some more helpful info there.

D20 modern squad