Casualty is the second stage of the Beginners Series in the Arcade Amateur League in TimeSplitters 2.
World Record Strategy
This strategy is for the gamecube version. On the gamecube version, there is one very good starting spawn that allows you to get 5 or 6 kills very quickly.
First, you'll want to go into preference and set the weapon switching to never. You'll have to switch to the lasergun at the start on you own, but you don't want the game deciding you need to pick up the electrotool when the lasergun is by far the weapon of choice.
Restart until you get the downstairs spawn where there is a lasergun straight ahead of you. Move forward and grab the gun, switch to it immediately, turn around and start charging a shot. Head back towards where you started and look through the doorway near where you started, which leads to an open room with a few tables in it. From there you'll see another large doorway and there'll be a zombie running into your view beyond it. Blast him before he runs out of sight and move towards the small room where he was.
As soon as you get there, turn to the left and there'll be a soldier enemy in another doorway entrance. Blast him three times, and check your radar. If you are lucky with the way enemies decide to move initially, there will be a zombie coming up just behind him. You can wait until he appears in the doorway and kill him, or you can head towards the doorway while you are killing the soldier and then turn the corner and blast the zombie, which is faster.
Head back to the small room and look out into the large room with tables. There'll be a zombie headed towards you. Blast him twice. If you are lucky, one of the zombies you've already killed will have respawned here. In that case, blast him.
Now turn toward the left to the small doorway that leads to the hallway. On your radar you'll see a zombie headed your way. Wait until he appears in the doorway and kill him.
From here, stay near this small room and hope luck goes your way with enemy spawns. Hopefully, enemies will spawn nearby in the large room with tables until you reach 15. Also watch your radar for enemies out in the hall if you get desperate for kills. Times of under 35 seconds are fairly good, and times of under 30 seconds are excellent and difficult to achieve.