Hiya!
We had a great idea about those multiplayer-adventures (2 or more player adventures). The main baseline of the idea, is common pool, where you could drop units of your choice, for everyone's usage: your friends can use your troops with their generals.
Now issue is ofcourse xp: your friend uses your troops to kill everyone, and you get losses, he gets xp's. Now this could be fixed with an option in the very beginning: When you start the adventure, you choose either the old fashioned way (current) or the pool-system. If you use the pool, the experiance points will be split evenly, no matter who's general does what.
This could also be for "between guild members only" -> one more benefit for joining a guild.
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The other issue is the combat. Now it is rather boring; you calculate every strike, and before you even attack, you will know how it will end and you know your losses. This makes the game unbalanced: Once you have made enough crossbowmen and cavalary etc. you can demolish those buildings, as you will only lose recruits. Sometimes you will lose occational cavalary, but you get those horses back as loot.
Now to fix this and give the game a little excitement and spin, how about good old fashioned settlers 2-type fighting system:
1) each unit has a number of hits it can take (recruit = 3, militia = 4 or 5) etc.
2) Units will then go fighting with that random game system, that they hit each other in turns, and the unit that gets the required numbers of hits to himself, will lose
3) They can of course block with shield, so there is a change of winning even you have recruit, and opponent is militia.. or something.
Or it could be something else, but now the combat system is too boring, you don't even bother to look at the replays (yes, that's what they are, replays, you already know the result, so no much of an excitment there). And the whole settler-economy-system is based on warfare -> everything you do is at the end of the line: make stronger army. You make foresters to make wood, to make structures that either builds weapons or resources for weapons, or they speed up your weapon production. Now when you get functioning economy, the end-line sucks, as there is nothing thriving in there, just pre-calculated obstacles, that you can use pre-written guides to beat with only recruit casualties. I don't know, is that the idea of the developers, that at the end, all that is used in the game (after you have enough all forces), is bread and bronze swords (in trade, bronze-swords become more expensive than say, steel swords).
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Something to think about.