You are trying to make a profit buying low and selling high on two different instruments. The two trades you need to make are called 'legs' in financial terminology.
Press to start the game.
Click the at the top to switch between instruments.
Choose to either buy or sell on either instrument by pressing the or buttons. You will execute at the best bid/ask.
Once you have bought or sold on one instrument, you have 4 seconds to do the opposite on the other instrument.
If you fail to execute in time, or make a loss - you lose. Try and get the highest profit possible.
You Lost!
> Your PnL is NaN
For more information about leg risk, and how it is mitigated in real life, check out this article.