From The TimeSplitters Wiki

Pane in the Neck
IMAGE NEEDED
Game	TS2
Section	Glass Smash
Map	Siberia
Character	Lt. Frost
Enemies Encountered	N/A
Rewards	?
Medal Requirements	Bronze: 1 min points Silver: 30.0 secs Gold: 18.0 secs Platinum: 11.0 secs

Those Russian soldiers aren't that bright! Today's military training involves breaking all the glass in the siberian compound. Nikolai managed this in one minute flat. Beat his time or you'll be the laughing stock of the barracks for weeks!

Briefing

Only using the grenades from the Soviet S47, you gotta smash all the windows in the level - remember that the grenade's explosion can take out multiple windows. A good way to get at least gold that isn't too challenging, is this -

Strategy

As you start, go forward and look towards the building to the north (has six windows, three on the top floor and three on the ground floor). Now as you run towards the stairs fire a grenade at the top of the building so it drops down and takes out all six windows. Take a left and go round the corner and pop a grenade into the building just here. Go ahead to another building ahead of you and fire a grenade into here also. Now go back and take the path that is in between the two buildings. Fire a grenade into that two story building that is now to the north east of you. You must fire it onto the top floor at the far right corner, and if done correctly will take out the one in the door and the three windows in the floor below. Then just walk on ahead and fire one through the door of the building ahead of you to the left. Volia! Done. If not all the windows are smashed, simply restart and do it again. This DEFINATLY does work, and you can get gold easily and platinum is also very possible.