Water turned to vapour by heat. Also a named games platform — context decides which.
Old English stēam (vapour, fume, steam), of uncertain further origin though old and widespread in the Germanic languages; a named games platform borrowed the plain word for the vapour of pressure and heat, not the reverse.
Water turned to vapour by heat, and elsewhere a named platform. Only context says which is meant, since nothing about the word itself tells the two apart.