NOVA RNA Lab
You know what's cool? Science, that's what. You know what's even cooler? Science games that can help save people's lives. As awesomely powerful as DNA is (see Play to Cure: Genes in Space for more on that), RNA is even more ancient and mysterious, and while we have a good understanding of how it works, there are so many ways it can fit together that we don't fully grasp the full range of things it can do. That's where the NOVA RNA Lab comes in. You don't need any special scientific knowledge to work in the VirtuaLab, as a wonderfully snarky computer guides you through the tutorial and the three subsequent pre-made worlds. Your goal in these early levels is to place the four RNA bases (adenine, guanine, uracil, and cytosine) so that your strand folds the same way as your goal image. Each bond and loop behaves differently, and there are different goals for each level. Once you complete the pre-made levels, the game becomes your toolbox, and you can not only build your own strands but vote on whose results actually end up being created in a real-life lab. If this sounds like Foldit or Eterna, that's because PBS teamed up with the people who made those games, and integrated a whole lot of improvements.
The lab's interface makes it easy to learn to play. You can paint individual bases or pairs if you like, but it's much easier to just paint entire strips by clicking and dragging along the areas you want to paint. You can switch between "goal mode" (which lets you see what your goal shape is) and "natural mode (which shows how your RNA strand will actually fold). The palette where you choose your base pairs doubles as a cheat sheet for what bases form what kind of bonds, and there's a "hint" option that walks you through each level if you get stuck. All this is to prepare you for the full lab, where you can create your very own RNA strands. What do they do? Do they fold up as expected? The world can find out! And in the process, we can maybe discover a specific protein that could cure a disease, or figure out the exact origins of life on Earth. There's more information available on the history of this game and exactly how it works at PBS's website. In short, the lab is an engaging way to learn science and maybe change the world.