@Nevod You get Amenhotep and upgrade him until you can unlock his "The Last Upgrade". Purchasing The Last Upgrade from him resets and gives you a world bonus.
It's odd that there are no upgrades centered around clicking. Everything seems to focus on passive CO2 generation. Really feels like no reason to ever click the fire after you start buying... anything.
 "Clicker Heroes"){kind=icon}
 "Bonfire"){kind=icon}
 "Monsters' Den Chronicles"){kind=icon}