itch.io

It's actually quite easy. Just read the description.

Here's an example:

You're a cosmic entity whose job is to create universes. However, there's a Cosmic Council above you that gives you objectives and tells you how your galaxies should be created.

For example, if the objective is Expansion > 80%, you press Initiate Genesis. Then, using the sliders at the bottom, you need to adjust the Expansion slider all the way to the right or at least far enough to reach 80%.

If you successfully meet the objective, you earn a point. To make things more competitive, there's also a global leaderboard where players can compare their scores.