As with all clicker games, many and repeated mouse clicks are needed to “achieve something”. Here, each click creates “green energy” (kWh) from solar panels and also some virtual coins. Using the coins, upgrades can be bought to produce even more energy. And.. well.. that’s it.
For a rough layout of upgrades and cost, I assumed a maximum gameplay duration of 10 minutes, where an experienced user could probably submit about 3000 clicks. Then, added some random upgrades, too, and also an autoclicker feature.