<prompt> Human: Hi!I am wondering if anyone here has worked on a technical level with stock simulators like the Marketwatch or Investopedia ones. How do they work? How does the game reconcile trades when they dont actually exist, and does it modify the data? Im looking at making one for research and dont know where to start. Thanks!  <response>: They likely dont make any attempt at price impact, if thats what youre asking. 