You can freeze your opponent in midair by using your pick axe over their head while they are either on a bar hanging, or falling through the air. If you do this, it will permanently keep them frozen and they will be unable to play unless you use the "kill player" cheat. Once they are frozen, a block of invisible land will remain where they are or were, and you can walk on it.
Open the main Lode Runner menu screen, then click the LEFT MOUSE BUTTON on the upper left corner of the menu screen and type cthulu or yog. A sound will confirm correct code entry. Press T, Y, U or G, H, J or B , N, M to control the monk. Press TAB to use the monk.
Go to level creator and make a level where a monk is trapped in a hole. Put a line of invisible ladders along where you want to walk just above the monk's head. Complete the rest of the level as desired or just add a treasure, an exit door, and a player and save the level. Go to where you can play the level you just made. Get on the monk's head. Start to walk off his head. You should keep walking, even though there is no land to walk on.