Alright, there is a lot of stuff here:

So, there is a variable in the game called "score_to_drop" that is given by:

The amount of players * Starting score + The variable "zombie_powerup_drop_increment"

"zombie_powerup_drop_increment" equals to "2000" at the start of the match.

Then, it puts the global score (the TOTAL score of each player) in a variable called "curr_total_score".

Then, if this last variable > score_to_drop = Drops a power up (then it multiplies the zombie_powerup_drop_increment by 1.14 but meh)

Basically, the more you go far in the game, the more points you need to get for a powerup to come, the less powerups you are going to get. Easy nuff?

On the internetz i found a tool to calculate how many points you need to get the next powerup : You must login or register to view this content.

All theAlright, there is a lot of stuff here:

So, there is a variable in the game called "score_to_drop" that is given by:

The amount of players * Starting score + The variable "zombie_powerup_drop_increment"

"zombie_powerup_drop_increment" equals to "2000" at the start of the match.

Then, it puts the global score (the TOTAL score of each player) in a variable called "curr_total_score".

Then, if this last variable > score_to_drop = Drops a power up (then it multiplies the zombie_powerup_drop_increment by 1.14 but you probably meh)

On the internetz i found a tool to calculate how many points you need to get the next powerup : You must login or register to view this content.

Don't quote on me that, but i'm pretty sure that the camping/running around does not affect at all the powerup drops, however, i reccomend to kill all the zombies when they are INSIDE the map, because it will never drop a powerup when you cannot walk (Behind the windows, and crap).

Exhaustive nuff?

Also, it's handy to note that zombies killed by the thundergun do not drop powerups