From The TimeSplitters Wiki

Boxing Clever
IMAGE NEEDED
Game	TSFP
Section	Behead The Undead
Map	You Genius, U-Genix - The Freak room
Character	Cortez
Enemies Encountered	Gilbert Gastric Jed Daisy Dismay
Rewards	Tin-Legs Tommy
Medal Requirements	Bronze: 5000 points Silver: 20000 points Gold: 50000 points Platinum: 100000

Boxing Clever is a TimeSplitters: Future Perfect Challenge. It involves shooting boxes at Zombies heads, this getting you points to gain the medals and rewards.

Briefing

Secret laboratory, blah blah... Twisted research, blah blah... Living dead, blah blah... Anyway lacking an immediate shotgun to hand it looks like the only way to get the heads off these guys is to hit them with boxes - so you'll be needing the temporal uplink's force manipulator for this one.

Strategy

All you have to do is pick up the boxes and throw it at the zombies heads. When there are too many, keep running in circles, dodging them until you're in a space where you can pick up a box and fire it at several enemies.

Although platinum seems hard, you get like 30000 from getting a combo x5. The more people there are, the more combo chances. Remember, that heads take off more, but are smaller.

When the amount of boxes gets low, wait until the end of a wave, and use that long time to pick back some, so you have at least 2 in the centre.

Platinum may seem hard to get, but when you get gold, and see your health, you should think you can do it.

Most of the time, you have to run around in circles to keep the enemies away.

Error?

After you've got platinum, at the end of a wave, you may lose points. 18000 points was lost after one person completed a wave, this meaning the guy got less point in the end then he did just before the end of the wave.