Loading time will be much longer than on the original Paper Minecraft. [1 to 9] - Select Item [Click] - Place or Mine [WASD] - Move / Jump [E] - Open/Close Inventory [E+hover] - Open / Close Chest, Crafting Table, Door [Space] - Drop single tile from a stack while dragging. [F] - Eat food [N] - Label a sign or chest [Q] - Drop item [P] - Pause / Unpause [T] - Talk / Command [O] - Save your game [M] - Music / Sounds [Shift] - Sprint
To open the debug menu, press the ? key. Another way of opening it is the ~ key, however, shift must be held while using this way. Thanks to @qucchia for the hacked blocks used for the ~ Shift and ? keys. Also thanks to @griffpatch for Paper Minecraft. Please leave feedback in the comments.