Directional TNT

A special type of TNT that when activated only blows a straight tunnel in a single way. To craft it, you would do the same crafting recipe for a normal piston, but remove the top layer of planks, instead having a single TNT on the top middle slot.

The directional TNT would have a maximum destruction of a 3x3x20 tunnel in the direction it is facing (with it's facing direction being it's Z), without damaging/destroying anything at it's sides or behind. The explosive power would be the same as the normal TNT. The more blast resistant the material it is blasting against, the shorter it's tunnel is (less blocks on the Z direction), so it will only reach 20 blocks long  if the material has a blast resistance of 0.

 If it reaches a point where it can't get shorter on the Z direction (it can only go 1 block), and there's still not enough power, then it will start sacrificing destruction power on the corner blocks(the ones diagonally away from the TNT), making a cross on the wall. If it's still too resistant to blow those blocks, the TNT will blow up only the central block (the one it's facing against). If that is still not enough, it won't do any destruction (for example if the wall it is facing against is obsidian, netherrite or bedrock).

These TNTs would be very useful for mining and opening space for building structures underground.