OK, cover 2 of possibly 4: a cover of Rvbomally's Divine Wind Absent,
http://rvbomally.deviantart.com/art/Divine-Wind-Absent-344648806 in which the Mongols succeed in overrunning Japan after 1274. Korea, a more favored vassal of the Mongols, ends up ruling large parts of Japan: although this does not stick in the long run, it creates a tradition of Korean interventionism in Japan.
The Yuan Mongol empire in China collapses as OTL, Mongols depart Japan by the late 1300s, butterflies go flapping all over. The Ottoman empire is butterflied away, and no single
Ghazi states rises to fill the role. Under a Serbian dynasty the Byzantine (or East Roman, as they call themselves) empire revives, albeit as a majority-Slav, Balkans-centered entity. Somewhat later than OTL, a Persian empire arises from the wreckage of Mongol Persia (Timur, too, is butterflied) and becomes the dominant Islamic power of the modern age.
Lithuania expands into Mongol-wrecked Russia as OTL, but loses most of its home territories to the *Teutonic Knights, leading the Lithuanian nobility to "go native" and convert to Orthodoxy: the unification of Russia begins in the south, not the Muscovite north (indeed, squashing the northern Russian states is such a job that the last holdout, the commercial republic formed from the union of Pskov and decaying Novgorod, is allowed to continue as a vassal rather than being directly absorbed.)
The Americas are discovered, but the timing is a bit different and it's a bit of a free-for-all from the start, with the French, English, Spanish, Portuguese, and Nederalanders all putting in an oar. The wars and quarrels over choice bits delayed things enough for the native Americans to get a bit of a breathing space, and opportunities to play off on power against another, although in most cases this simply delayed the inevitable.
This world's version of the Reformation largely failed to get off the ground, and although protestants are still tolerated in some parts of the former HRE, the only states to actually have non-Catholic dominant religions are Sweden-Norway and Hungary, with Hungary having an Anglican-type "vanilla" Protestantism. They are considered "weird" by the Catholic major powers, but generally tolerated nowadays.
In the mid-18th century, the Big Four Catholic powers joined to defend central Europe from an aggressively expansionist Russia and its "Roman" ally. (This alliance also served the purpose of putting an end to a series of costly colonial wars between England, Portugal and France). Unfortunately, in the 19th century the Portuguese empire broke up as conflict arose between increasingly independent minded colonials and a centralizing absolutist homeland: the
very unhelpful attitude of the French and British during this process led Portugal to dump it's long-standing alliance of convenience with the British, and eventually depart the Catholic League entirely.
It is now 1930 AD. Tech is roughly OTL 1910-1914, wee biplanes, airships, lots of rail-building and radio just starting to really catch on. A new threat to World Peace has arisen in the form of the Pact of Bronze, an odd alliance between two ambitious, rising Asian powers and the resentful *Fascist dictatorship of Portugal. Portugal wants to regain lost colonial territories, and crush the troublesome left-wing regime that infests Castile next door. Korea-centered Goreyo is hungry to "liberate" the European colonies in the area and put an end to any foreign meddling in "their" Japan/Nippon. Persia hopes to expand into the remaining Middle East and liberate Egypt from the Christian Menace (a badly decayed Mamluk Egypt was overrun by Byzantium in the mid-1700, and remains under the thumb of Orthodox colonists and their local Coptic allies: the Muslim majority is however improving it's insurrection skills, and the Persians are happy to provide education abroad...)
Currently there is a bit of a thaw between the Catholic and Orthodox powers, which strongly dislike eachother (The Polish War devastated half of Europe for a decade with no real victory), but are even less tolerant of these "upstarts." Conscious of the danger of the Catholic League and the Holy Alliance joining forces, the Pact is trying to recruit new members and run up a peace offensive with Russia, which doesn't really have too much territory worth stealing.
Politics are fairly authoritarian, if perhaps _overall_ not as bad as our world would soon be in the 1930s. England has universal male suffrage and a strong parliament, and while the French and Bohemian-Bavarians are less democratic, monarchic absolutism has had its day in the Catholic League. Not in the Holy Alliance - Byzantium is as absolutist as OTL Russia in 1914, Kievan Russia is even more so with added secret police, and while there is some internal democracy in the ruling Christian elites of Egypt, the Muslim majority is very firmly kept in its place.
The Pact of Bronze is Not Nice: Persia is as brutally authoritarian as Kiev, harshly efficient Goreyo is fond of Collective Responsibility and Death With Extra Torture Sauce for a great variety of crimes, while Portugal is Clerical-Fascist with a megalomaniacal supremo who is trying to make up for a dinky white population with mass African and Asian slave labor and slave troops.
Bruce