Steam is a color matching game with a strong arcade element. The player controls Tisha, a little girl riding a steampunk locomotive shooting colored balls from a mounted cannon at ball dispensers (in the first levels they are mole mounds). The train tracks circulate those dispensers as they keep filling the inner field around them with balls. Matching 3 or more balls of the same color makes them disappear. If the spheres accumulate, a floating time bomb appears. Its detonation ends the game.