Alright, this time I was able to play with the "Start Level" button! :D
I still think that the tutorial prepares for a much different game than the actual one. It is good for teaching the mechanics. But maybe it could have a last example of how an actual open-ended level looks like?
This time I managed to complete all levels! And it was satisfying. :) There was situations were I felt that I had to make strategic choices, and felt rewarded when they worked. There can be a nice synergy between the different blocks. I sometimes had to start "early" because the piece just couldn't fit anywhere. Some of them had kinda weird shape that takes a lot of rooms, and some level don't have a lot of space.
Also when the next 4 pieces don't contain pearls, I'm not sure if it's worth continuing to place them? Globally I had more fun when I had to shape the path of the level. Adding "noise" blocks that don't lead to pearls was less satisfying. Although it is also part of the challenge, but when there's only those in the pool for a while my level-design feel useless. The best times were when I'd have "interesting" pieces that had a bit of synergy between them and built up to an almost consistent level!
I'd say the game loop works. However I don't know if the scores I got were good or not (I was at between 1200 and 1900).^^' Perhaps a target score, or a system of rank/medals could give an incentive to play strategically?