i don't think its "technically" possible.
if players will find bigger fun fighting with big fishes than against them, if most of the people will prefer bipolar world over multipolar, this game will always have some UIF, EIF, UEF, EEF, UOF or whatever. Even if UIF won't reform, sooner or later there will be someone else with bunch of bootlickers behind him doing the same thing (conquering most of the map).
has anybody seen any game with alliances that would finish differently than with 1vs1 huge alliance fight? me not...
Sure people naturally want to join in on the big groups - this is nearly always the case. But if you make the game mechanics (the strategic ones, not the fighting ones) so that it isn't always best to do that, the game will be more fun.
If the game is simple, alliances will always be better. But if you add in other factors which make it more realistic (in this case realism adds to gameplay), alliances aren't always the best idea.
I can think of three big ways to do that, but I'm not sure how easy they would be to add, or how they could be added:
1) Economics and topography: if you have resources randomly distributed, it gives something else for people to fight for. And it gives more reasons for people to fight, rather than make huge alliances. Factions will want to control resources either through alliances and trade, or capturing the resource. The more factions there are, the more difficult it will be to maintain resource-monopoly alliances (especially if the resources have a time based limit - you need workers to produce them over time or whatever). Adding topography (another mechanical limit on resource distribution and logistics) will further complicate things, as well as army upkeep and supply lines.
2) More influence for non-faction players, or smaller factions: this can be achieved in many ways - economics is one of them. If the players can represent skilled craftsmen or women and work in your fief, it gives them more power individually. Also the ability to be a bandit - raiding caravans. The more ways you can find to give non-faction players more power to counter balance the obvious benefits of joining a faction, the more stuff factions will have to think about.
3) Social factors: this I think would be very difficult and maybe controversial to add. But if you force players into a government role only (not representing the population of their fiefs), you can make politics and diplomacy much more difficult - not so obviously beneficial to just form a huge alliance. For example, you could add mechanics like civil unrest, resistance to occupation, and xenophobia, or even something like religion or ideological beliefs. So making alliances with a faction who your people hate would cause your faction to be unpopular with it's people, and you get riots.
So, going to war or making an alliance involves thinking about more than just 'if I get this fief I get more money and more soldiers', or 'if I ally with all these other players I'm completely safe'.
Obviously there's way too much stuff there to add, and probably a lot of it wouldn't work or would be to complicated. But the more stuff players have to consider, and the more factions there are playing (as well as more power and use for players who aren't in a faction, and more impact - for example through raiding or banditry), the less obvious it is that huge alliance blocks = good.
If someone asks you for an alliance and you have to think about the cost of the alliance before you say yes, it'll stop the bi-polar stuff. Imagine if you have to pay upkeep for armies and supply them with stuff, or to help defend their territories you have to move your armies through a mountain range, or they just don't have any resources that you want, or there is proper fow and lots of non-faction players are waiting to raid any caravans you might send. Or even that the people who live in your fiefs hate the people who live in their fiefs, and if you ally with them you get civil unrest.
Point is, the more realistic (within reason) you make the strategic aspects, the more realistic alliances and diplomacy will become. And adding even a basic economy will always increase the amount of wars and decrease alliances - as soon as alliances become economic as well as just simply military, they become much more difficult to make.
And anyone who played Risk with alliances between players allowed is insane
