Pre Create Performance Task Idea

In preparation for the upcoming AP exam, our class is doing a project where we each create an app, game, website, or some other representation through coding and give each other feedback. My idea for this project, is to create a game where obstacles are randomly generated and you control the object that is trying to avoid them. I want to make a score counter and a leaderboard, as well as a start game button.

I do not yet know how to get the randomly generated blocks to come in, how to use millis to control time elapsed in game, or how to represent a scoreboard. I will attempt to learn this by using multiple libraries and basing my code off of reference material from these libraries.