Nah, I'm pretty sure it's coming from the lack of tutorial. Or at least text boxes describing in-game elements. I had a lot of ideas for that but couldn't implement them in time.

So let me unroll the gameplay loop :

In "Tasks panel", you can choose a key to forge, it will display a green pattern  in the main frame at the center of the screen. Using grey shapes in the left section (above the shop) and dragging them (+ mouse wheel to rotate) in the frame, you can try and complete the chosen pattern.  If you can match the pattern with you current shapes, you 've go two options :

• Buy new ones in the "shop", by simply clicking the shape you want to purchase (if you have enough points - purchasable shapes have their name displayed in white)). It will be spawned in the left top section among others 
• Open the "melt and cast" panel and drag and drop a shape you already have on the black cauldron thingy to melt it and retrieve its worth in iron drops. On the black square next to it , you can smith a new piece using your iron drops. To use the casting mold , you can click on each cell to craft the shape you need (I note that I should had cell subdivision on it for more clarity). Click on a cell multiple times to cycle between every possibility. Once you get what you need and, if the shape is not too litttle (to avoid too easy solutions), click cast to spend your drops and get your new shape. It will be spawned among others in the top left section. You can now add it to the main frame.

If your frame match the green pattern, you can click "forge" right above and you can pick a new "task" to complete.
Hope it helps, either you if you want to give it another try or anyone that would come next !