Funny you should ask, as we just played our first three-player game last Sunday.
One of the published scenarios has one side with two players ambushing the other player from opposite sides. I think this sort of scenario does not usually work out well, but in this case it did. Great way to introduce another player into the game.
Although I have not tried it, I do not see why multi-player games, such as with traditional miniatures games, could not work. The "problem", of course, is that each player takes their actions in turn, so the more players, the longer the wait before it is your turn again. That problem exists with a number of games; really no different than, say Monopoly. Turns in Abaddon are fast enough, and interactive enough, that people should not get bored waiting for their turn.
As much as I like this game and enjoy playing it, for me it is clear that we will never see more of this ...
Richard Borg hinted on new material, but let's face the truth: this game is unfortunately not doing well. And I think it is because of a total failure of marketing - any game of Richard Borg where C&C meets SF should have done better than this. But a game where I have to sticker the dice and the minis (happened the last time maybe beginning '90), a rulebook that is - well "bad" (and more or less all the diagrams are wrong), missing Terrain rules (or why are there three types of Terrain) and finally the box insert and these cups It seemed ToyVault never was interested to get it to continental Europe and even in the US it seems to be failing.
Still I would be very interested getting new content for this - even online, as I am sure we will not get the expansion, that was in the planing for sure (or the other way around, the base game feels incomplete...)