From The TimeSplitters Wiki

Brain Drain
IMAGE NEEDED
Game	TSFP
Section	Behead The Undead
Map	Hotel
Character	Dr. Lancet
Enemies Encountered	Infinity Brains
Rewards	Bronze: Brains, Rotating Heads
Medal Requirements	Bronze: 5000 points Silver: 15000 points Gold: 25000 points Platinum: 35000

Brain Drain is a TimeSplitters: Future Perfect Challenge. It involves decapitating as many Brains as possible, this getting you points to gain the medals and rewards.

Briefing

For years now, Dr. Lancet has been cutting the tops of cute little monkey's heads just as if they were hard boiled eggs. When he's finished poking at their cerebellums he illegally dumps the remains in an alley behind the vivisection lab. You just can't expect to get away with that kind of stuff... well at least you should finish them off properly with a shotgun.

Strategy

On the first few waves, run left, shoot off the monkey's head, turn right, run forwards and shoot off that monkey's head and any other Brains that come you way. Do this for the first 3 waves, and you should get 3 perfects.

On wave 4, do this, but watch out for the Brains that have shotguns that appear on the right stairwell. Also watch out for bats. And remember to keep picking up the shotgun.

You don't need to shoot at the weird flying things a lot, they normally get taken out while you're shooting the monkeys.

On Wave 4 and up, run to the monkey on the right, look up, wait for the shotgun monkey to spawn and shoot him through the wood space. If you ever see the blue light from the top of the stairs, stop and shoot him, most of the time you knock off his head no matter what distance if you aim at him. If you didn't he should have still been hit, this giving you time to reload before you shoot at him again or time to get ready to aim. If you see him and are been shot by him, keep on moving around the foot monkeys but shoot at the shotgun monkey.

When attacking the foot monkeys, you can run from next to one set of stairs to the other, avoiding them as you run and shooting. Try and get combos, although you still get the same points, it's cool and saves time, especially with the long reloading shotgun, and 2 shots to every round.

Try and get the shotgun every time it spawns, or you go near it, do this, and the more it will appear.

Using this strategy, a platinum is easy, and once you can get the hang of it, you can at least get 50000 points.