Gates are hazards in the game Knuckleheads, appearing mostly in the later levels of Knuckleheads. Gates are hazards because, if either one of the angry heads touches the metal of the gate, a life will be lost.
Gates appear as large metal grids with bolts holding the metal rods of the grid together. At the bottom, the metal rods end in pointy spikes that touch the ground when the gate falls.
Gates are harmful, but not deadly, to the angry heads; gates rise up and then drop down in a perpetual cycle. If either one of the angry heads touches the metal of the gate, a heart will be lost, and the angry heads will roar in pain. However, if the chain touches the metal of the gate, nothing will happen- the metal rods will simply go right through the chain.
If the angry heads touch the gate three times, then the chain between them will shatter and they will die, falling down into the lava below. The gate will rise up, stay in the air for a moment, and then fall, over and over again in a perpetual cycle. When the gate rises, it leaves enough space for the angry heads to move under it, but not enough room to extend the full length of the chain.