Hi
Here a link which simulates a high frequency trading desktop:
https://traderstrophy.com Just press: Try our trading simulation. You have to answer the calls and you have to trade according to market moves and according to your open positions.
If you want to work in such a company, you have to pass three different tests. Here a link which will give you an idea how such test look:
http://tradertest.org.
Good fun and to not forget where you placed your easter eggs in the garden or in your house.