In this game mode your objective is to get the highest possible score by packing the least amount of bins and packing the bins as densly as possible in the top right strip.
Your are competing against an algorithm. It has the same objective as you.
The left part of your is your inventory. This is all the rectangles that you have yet to pack. To pack one of these simply drag it to your strip.
Each rectangle will be given a number when the algorithm packs. The number indicates which rectangles the algorithm has choosen and in which order.
In the bottom right corner of your screen you can see another strip. This is the strip where the algorithm packs its rectangles. The algorithm has the same inventory as you do.
After you have placed a rectangle the algorithm will do the same. The numbers that appear in the inventory is the order of which the algorithm has selected the rectangles.
You can always open this again by clickingin the top right corner