Bomberland

Bomberland is the setting of the game Wario Blast: Featuring Bomberman!

Bomberman series
The setting of the original Bomberman game was an unnamed underground labyrinth controlled by the Bungeling Empire. Bomberman himself was a bomb-producing robot encouraged by a rumor that robots escaping to the planet's surface become human. In subsequent appearances, the planet appeared to be Earth, but was later named and revised as Bomber Star (aka Planet Bomber), one of many locations in the Bomber Nebula.

Wario Blast: Featuring Bomberman!
Wario somehow has found the extra-dimenional portal that links his world to Bomberland. Thinking of claiming the riches and people of Bomberman's world as his own, the greedy character entered the portal, but was met with more resistance by the Madbombers than he'd anticipated.