Kill Early, Kill Often
To get the gold medal, you need to score 40 kills in a minute and thirty seconds. That works out to having to score one kill ever 2.25 seconds, which seems damn near impossible at first. But with the right strategy and a bit of luck, the mission can be accomplished. As soon as the game starts, don't waste any time. Immediately open fire at everyone you see. In the left screenshot, I've scored 2 kills within the first 4 seconds.

Hiding Out
Open areas can be quite hazardous, especially with all those explosives flying around. I've personally found that this big, open brick wall room is an excellent spot to wait. Although you're technically "trapped" here, it forces your enemies to come to you, so you can blast them as soon as they enter either doorway. You can't just stand still and wait however. It's best to quickly strafe around the room, repeatedly scanning each exit. When you face a number of intruders, fire while backing off, and try and get a bit of cover behind the wall.

Keep Up The Pace
Peeking out from behind the wall, I'm able to fire explosive blasts and take out groups of enemies. Since this is an awkward position to find yourself in, be sure to keep moving. Fire a few rockets, then sidestep to avoid the rockets that are being fired at you. Fire your own rockets at the feet of incoming opponents, and even simply fire at the wall if an enemy is close enough to it. In the right screenshot, you can see that I have 25 kills in 44 seconds so far. This is exactly the kind of breakneck speed that needs to be maintained to succeed here.

Homing Missile Launcher
The Homing Missile Launcher can be a devastating weapon, but it's not always the best choice for this mission. Out in the open areas, against distant enemies, the weapon works like a charm. But for close range, the Rocket Launcher is probably your best bet. In the right screenshot, you see me firing at the pavement in front of a foe. Direct hits will certainly score kills, but it's often easier not to aim at your opponents, but fire a rocket into the ground or a nearby wall.

Shooting Down From Above
There are walkways on some portions of the streets where the ladies will run and try and surprise you. Keep an eye out overhead, and lead your targets by firing rockets ahead of your enemies as they run on the walkway. In the right screenshot, you'll see that I'm holed up in another corner. There's no way out, and I know I'll die eventually. But being in one area like this allows you to take out clusters of enemies before being killed yourself. The tradeoff for scoring a dozen kills while losing one life is pretty damn good.

Walls and Floors
As mentioned earlier, directly shooting at your foes isn't always the best option. Nearby walls where your opponents are standing make excellent targets, because the explosion on the wall is often enough to kill an enemy. In the right screenshot, you see me firing yet another rocket at the feet of a few enemies.

Absolute Chaos
With all the explosions and constant death, this mission can be a bit discouraging. But just remember, it doesn't matter how many times you are killed. Charging headfirst into a pack of rocket-maniacs is a dangerous move, but if you can take out the cluster with a few well placed rockets of your own, you can rack up a lot of kills.

Final Thoughts
This mission is challenging, and could take a dozen tries or more before the Gold medal is awarded. Also keep in mind that a bit of luck can also play a part in your success, and restarting the match after a poor start isn't a bad thing to do. For this challenge, you need to make it your personal mission to destroy as many enemies as quickly as possible. The Rocket Launcher isn't the easiest weapon to use, but practice will help you learn to use it effectively. Once you get the technique of scoring plenty of kills, the next challenge is to actually do it all in 1:30 or less. I was consistently finishing in the 1:40s, missing out by just over 10 seconds. But a match with a few lucky instances saw me finish in 1:23 to capture the gold.