Lava Powerhouse is the second level of Sonic Spinball for the Mega Drive/Game Gear/Master System, coming after Toxic Caves and before The Machine. As with other stages in this game, Sonic must bounce through the pinball-like level, acquiring Chaos Emeralds which are in turn used to access the boss. In this stage, there are 3 to find.
Lava Powerhouse is a geothermal energy plant, fueling the robotizing factories (where animals are turned into power sources for robots) of the Veg-O-Fortress' higher levels by tapping the magma flowing through the core of Mt. Mobius. Steam-driven pistons and pressure dials abound, in addition to giant bellows crewed by odd blue kangaroo Mobians.
This is the first of two levels in the game where the player can score lots of points by earning a score multiplier - this is done by lighting a series of gates that are found at the tops of the bottom rooms of the level. When a gate has been passed through, the light above it turns yellow, and lighting all three increases the multiplier by one (so for example, doing this once doubles all scoring, twice triples it, and so on). Showdown is the other level in which this can be done.
The boss of the Lava Powerhouse is the Roboiler, a strange tank containing four robotic heads, each resembling Doctor Robotnik. Each head can move to one of five locations in the boiler, and they seem to vomit lava whenever Sonic hits them. Sonic has to destroy all four of the robotic faces by jumping into their chamber and rattling about; but whenever one gets taken out, the remaining heads will temporarily vanish, leaving Sonic to tumble out of the vessel and have to make his way back up.