It's closer to Rumble World to Fullblox.
http://www.serebii.net/picross/picrites.shtml
You don't buy more courses, you buy Picrites which can be used to speed up recovery time or to unlock new areas.
There's a top limit of the amount you can buy which then seems to make things a bit easier to stomach, just like Rumble World.
You can play it all without paying a penny.