As I told in an other thread,
[color="#40E0D0"]http://www.ageod-forum.com/showthread.php?32665-Kensai-s-Gro%DFdeutschland-Mod[/color]
the really historical (I mean historically plausible) alternatives to historical (Prussian Germany) are twofold
a)
realistic Habsburg "German Empire" confederation, respecting princes : that is except for swap Silesia/Venetia (Lombardy is already supposed Italy's), and possible Prussian western provinces losses to other allies (and France, price of her neutrality) that is Bavaria Hessen and Hannover are likely beneficiaries, you have the following pattern, in game system terms :
customs union, permanent alliance, and set AI diplobias of german Austrian allies to maximum for alliance and support, zero to CB and war, and as an addition make a maximium of them playable if you want have them really controlled, but do not annex them - then balance is preserved and this is a rather historical option (this one planned by Napoleon III and I believe Franz Josef, except that actually, the preferred scheme (he had many) of Napoleon was more favourable to Prussia, who lost a few western provinces and Silesia BUT annexed Hannover in compensation (which was both a Napoleonic proposal tradition, and likely not to be of Austria taste
b)
Pangermanist Groszdeutschland : if you want to be realistic, have Austrian leaders moved and changed by other leaders (some research to make, it's alternative history). In this alternative, German people overthrew princes in a popular therefore revolutionary move (probably with support of far right upper classes representatives (Nobility, big Industrial) who found useful to deflect German feeliongs and unrest towards national rather than social revolution (sounds familiar to you ? in other circulmstances ?)
THEN the new Greater Germany (it is imho a plausible, as internally consistant, albeit unlikely, course) is neither Prussian nor Austrian :
- Whole Prussia is in (They won't ask Poles their opinion), Sleswig is,
- minor Germans all are,
- Bohemia is in (historically + strong 1/3d German minority - Czech want to be out at all costs, but their opinion is not and will not be solicited, they were in the HRE, this is an exacerbated German nationalist state, pupular passions, you see, wacht am Rhein, was is die deutsche vaterland and so on .)
- so is Slovenia-Croatia, with less problems (alternatives are Italy or hungary, no more desirable)
- and so Cisleithania is in, with reservations for Poland-Galicia - you can choose any option you want, transfer to Hungary, keep the whole, share with Hungary (having her independant is not an option, there would be irredentism, so it is german , Hungarian, or Russians will annex it which is, from a german nationalist point of view, untolerable)
Hungary is out (no way Hungarians would have accepted a second rate situation in an ethnic german nationalist run Empire
still they are good frinds of the new united germany (watch your hordes, we'll watch ours)
geographically, Hitler third reich is very close (surprise surprise), and so is ideologically - except for murderous antisemitism (while ... if ultranationalism gets loose ... it's not specific to germany, watch the Russian extreme right, or even the Affaire dreyfus) - here too, logical, Nazism takes root in an history and a preexisting ideology ...
this is 1848 success, with an even more acute and agressive nationalism (it is later in the century)
new state has common interests with Hungary (is a buffer), terrible relations with France (nationalism is exacerbated, getting Alsace Lorraine is a most important popular demand, nationalism has been exacerbated in full peace, no conservatism there acting as a brake - or they got it, and the historical revanche feeling drives France, same trend) and Italy (ditto, same Italian irredentism)
with Britain, it depends on colonialism and naval policy, plus balance
with Russia it is more subtle, on one side Russians don't like the way Czech and Croatians are treated, on the other they care less (far away and Catholics , not Orthodox, it martters a lot), the big frictions are with Hungary, balkans
so same german/ Hungary-Russia problematics than German/Austria-Hungary - Russia, Bismarck can rest in peace
so, all in all the greater germany will look a lot like the cerntral powers, a german hungarian alliance, with a minor partner, but a
displacement of center of gravity (germany annexed Austria, not Hungary), even if capital is Vienna and not Berlin, for a centralized state it changes little, and a German leader of Austrian ascent can lead a very agressive and pangermanist german policy, you see ...

one has seen such things happen ...
this is a plausible outcome (make AiBias and playability provisios for coordinating with Hungary, set Hungary goals closely too ..) too, while less likely than the Habsburg victory one
both have the advantage of allowing a game with Balance of power (OK, germany ios WAY more powerful with Austria+Bohemia but this remains manageable - central powers have the SAME global oôwer, just more efficiency)
as I told, your unitarian unified great germany is an interesting scenario BUT seems to me, AFTER analysis, least plausible, not that much because it has to overcome non german nationalistic feelings (expect have to crush Hungarians again, this time without Paskievitch help) but because it has to overcome Franz Josef and conservative feelings, which is imho a bit tougher (they're the
ruling class you know)
still, your choice, and i know our limitations - ability to have common peaces and managing allainces (terms for allied gains, control of allied forces, at least mionors, is in top of my wishglist .. a far prospect)
cheers
