From their announcement:
This is a pre-release version of Tomorrow’s War. It requires Force on Force to play, but we’re providing a bundled version of Tomorrow’s War and Force on Force at an incredibly low price: $20usd (the expansion may be purchased separately for $15d by those who already own Force on Force). This version contains all the rules needed to play gritty hard science fiction miniatures games and includes sample vehicles, unit organizations, and four original scenarios.
So what’s difference between the pre-release version and the full version slated for release in September of of 2011 from Ambush Alley Games & Osprey Publishing? For starters, the full version will be offered in both print and PDF versions. It will also be a stand-alone rule-book and will not require Force on Force to play. This pre-release version doesn’t contain our extensive (but purely optional) game setting or all the eye-popping artwork that will grace the full version, either. What it does contain is 81 pages of rules, sample vehicles, organizations, and scenarios plus 72 brand-spanking new, science fiction oriented Fog of War cards.
So, why a pre-release version of Tomorrow’s War? Why not just wait until the full-version Osprey edition comes out next year? Simple: Over a year ago, before we’d entered into partnership with Osprey, we made a commitment to our customers to release science fiction rules by September of this year. We see no reason to break a commitment to our customers just because it would be more convenient. By offering this pre-release version, we give our customers the option of waiting for the stand-alone Osprey version or getting a head-start on Tomorrow’s War today with an affordably priced, utilitarian expansion.
You can learn more about Tomorrow’s War (and purchase the it) at http://ambushalleygames.com/TW.html