Android testing - simulate multiple users

I'm a beginner in testing applications, so I have many doubts. My app is a game where users play with others. Game starts at a certain time and finish in 60 seconds. During this time players play together, and when game is finished the score will be saved on mysql db with php.

So I would like to test what happen when many users (for example 1000) play together. Manually I can't simulate so many users. There is a simple way to do that? Now I'm starting to use JUnit and Espresso for testing.

Thank you very much, and sorry for my bad English.