question: what is the goal for these challenge puzzles? Just solving them how ever possible within the restrictions presented?
The challenge puzzles have several purposes. As you said, the puzzle is solved as long as the structure forms with the restrictions provided for that puzzle. The challenge puzzles provide an important way to hone your skills for the lab puzzles. You get to see much more variety in all the different challenge puzzles than we can accomplish for the lab puzzles, where we are limited by how fast we can do experiments. Doing the challenge puzzles teaches you a lot about how to design an RNA!
Additionally, the challenge puzzles let you help us attack problems “in silico” - just with the simulations of the RNA, not actually synthesizing the RNAs (yet). Having lots of people solve the challenge puzzles will help us find patterns for what sequences we think will work for a given design.
Hope this helps!