The game requires a considerable time investment in the long term but not a great deal of time on a daily basis. Your workers are limited in number (only two at first), and some projects require many hours—and sometimes days—to be completed.
There are other activities that don’t require workers, such as breeding monsters, running dungeons, and fighting PvP battles, that you can do while waiting for work to get done, but they also have downtime built into them.