The nuker is a player weapon in Hacx. Shaped like a yellow funnel with a Nuclear symbol on the top, the nuker fires, presumably some sort of nuclear material containing canister that causes heavy damage to whatever it hits. Following that, anything nearby is then hit by smaller explosions. It is simply a faster Doom's BFG9000 with different graphics.
The nuker is effective against everything: It will destroy most monsters in one shot and its fast rate of fire makes it able to face almost any threat. However, because of how fast and how powerful it is, it is the rarest weapon in the game, and it consumes ammo extremely quickly.