Ah, Allegiance - I knew all about that game back when it was actually on sale, and that the source code had subsequently been released and the title was now freely available, but I have never even been slightly interested in it even though I happen to freaking love space simulators.
Why not? Multiplayer-only. Juxtapose whatever you want, hype the amazing and innovating gameplay, release to rave reviews, it won't matter, those words are the kiss of death (of any interest I might have had in your game) - I don't play multiplayer-only games. Or rather, I don't play multiplayer-only games that are not online RPGs with no subscription fee.
Allegiance, at time of release, was essentially the worst of both worlds - an exclusively multiplayer title that they wanted me to pay a subscription fee to play. I've made it very clear over the years that my "I will not EVER under ANY circumstances play a game that has subscription fees" stance is utterly inviolate - there is no even remote possibility of my ever capitulating and compromising that point, so as interesting as the mechanics of Allegiance sounded (and they did sound pretty damn interesting, in principle anyways), it was never going to work.
Releasing the source code, modding the game, and establishing community run servers are all great moves that have extended the lifespan of what sounds like an excellent space sim, but none of that eliminates my complete lack of interest in a non-RPG online-only multiplayer space sim - that isn't what I'm looking for from that genre, and my single-player campaign needs are ably met by Freespace 2 (the greatest space sim ever released, bar none) and it's own source code project.