From the review:
While you can find more fantasy and sci-fi skirmish games out there than ever before... there's still somewhat of a lack of superhero miniatures skirmish games available. At present, and not including HeroClix, there's really only two notable products in this genre and that's SuperSystem and Pulp City.
SuperSystem has been around for years now, and it's one of the most memorable superhero skirmish games available for miniature gaming. The most current version of SuperSystem is 3rd Edition. The easiest way to obtain Supersystem 3rd Edition is to purchase the .pdf version for $10.95. There's a hard-copy version available too for $25, but it seems more elusive to find in-print.