try surfer 8 for isometric mapping.... though not specifically for gaming it does offer 3d graphing from x,y,z sets... which can be rotated to any view you like ..... though i dont know about the transformations algorythms and whether they are isometric......... technically they aren't since x,y,z is 3d and you want 2d isometrically transformed to 3d...... correct??

anyways sorry to blather about .... just try google sketchup it rocks!!!!!