The effort went into backgrounds, sprites, and other stuff like that. If you want human, elf, whatever sex in the future - those assets need to be created. The new places need to be coded. CGs are the bare tip of the iceberg when it comes to the effort required to create this game. Again, speaking as an amateur artist - it takes a long time to draw and render a single character with any real detail like Nomo's. It takes much longer to do a background. Now make that multiple new backgrounds, multiple new character sprites with multiple variations, and so on. If all they wanted to do was churn out CGs they could have a dozen out every two months - but it would be terrifically dull.