Players must mow a certain percentage of their current area to unlock the next world. There are at least 20 different worlds, including themed environments like the Dry Desert and Winterland.
You can upgrade your "rusty noob" mower to more powerful versions, eventually reaching "Godly" status. After clearing 20 worlds, players can use the rebirth mechanic to restart with permanent bonuses.
Watch these gameplay videos to see the progression from a new player to unlocking high-tier mowers and worlds: