Space, W, or up arrow to jump. A, D, left, and right arrow to move left and right. Solid blocks prevent you from going in. Slime blocks let you go inside, you will fall a lot slower inside a slime block. Zipline blocks let you stick on the bottom, you can also go inside a zipline block by jumping and going through the side. You get an extra jump after going on or in a zipline block.
