For a far nastier enemy, there's Nazi-dominated Reich-5. A world where the axis powers won World War II fifty years ago, and an aggressive high-tech Germany and Japan now rule the entire globe, they've gained access to a limited number of other worldlines with the aid of Aryan occult mysticism and some psionic bio-tech that's unpleasant enough to warrant being called black magic. Now they're slowly spreading their reign of terror across other worlds. Unlike Centrum, they don't go for subtlety when brute force will do the job, and have no qualms over unleashing high-tech firepower on the inhabitants of primitive worlds. The only thing slowing them down is that their form of dimensional travel won't let them move a great deal of heavy equipment from world to world, so their offworld stormtroopers tend to be relatively lightly armed and equipped. They're the foe for games when you want an old-fashioned morally unambiguous Good versus Evil slugfest.

Then there's The Cabal, a world-spanning alliance of enigmatic entities such as immortal sorcerors, vampires and other assorted supernatural beings. The Cabal make an opponent for a game focussing more on horror or dark fantasy. Finally Homeline has villains of it's own, from corrupt corporations to organised crime syndicates extending their tentacles beyond one Earth.

And I haven't even mentioned the parachronozoids or the reality quakes yet.

Next, Present at the Creation is a toolbox for creating your own parallel worlds. It gives a lot of advice on creating plausible histories. First it describes the various kinds of infinite worlds; from Echoes (copies of homeline at an earlier point in time), close parallels (like Homeline but with a few minor social or cultural changes), further parallels (with major changes in history), high inertia parallels (changes in history centuries or millennia ago, but which still retain recognisable cultures), and myth parallels (those that resemble mythologies, or even popular fantasy fictions). I personally find the last of those rather silly, and won't use them in any Infinite World games I ever run! Your mileage my vary, of course.

It contains a random world generation system, in which you roll in turn on tables determining technology, number and type of major civilisations, and the government structures of each. To test this, I came up with a world of modern-day technology, dominated by a caste-based West African empire, and a bipolar Japanese/Chinese civilisation, comprised of a dictatorship and an oligarchy.

Worlds Enough gives a couple of dozen ready made parallel worlds; each described in a couple of pages. Many of these are old favourites from the two Alternate Earth books. Examples are the improbably Aztec-dominated Ezcalli, the steam-powered Roman Empire of Roma Aeterna, the futuristic high-tech Moslem-dominated Caliph where the industrial revolution took place in 10th-century Arabia. These brief descriptions don't replace the two AE books, to which GMs wanting further information are referred. Alongside these we have plenty of all-new worlds, including Bonaparte-1, the post-Napoleonic cyberpunk one I remember Ken Hite discussing at Gen Con UK a few years back.