For me there's just something about a ravenous, unrelenting tide of monsters devouring everything in their path. I also really like their fluff and the various bits of artwork produced.
...that said, i don't actually have a Tyranid army... yet.
The answer is simple - Starship Troopers.
Having an antagonist faction that has no personality really appeals to me as a contrast to the other more human factions.
2) What he said exactly.
4) Reading about the fall of Tyran http://warhammer40k.....com/wiki/Tyran really did it for me. Something about that alien feel. The smugness of the defenders when they wipe out the first few waves. Until they realize that was the scouting party. When the laws of math state that the amount of ammunition they have simply, mathematically, is not in their favor against what they face.
5) This might be the strangest of all, but reading about the fall of Tyran above, and subsequent material on them has awoken the inner scientist in me. Emperor help me for sympathizing with the Brad Dourif character in Alien: Resurrection, but there's a certain fasincation. A need to learn, a need to study them that makes them so interesting. Perhaps even stranger is the fact that I somehow sympathize with the chronicler of Tyran. The idea that you are already dead but must chronicle, and catalogue, and document every detail you can so that others may learn from your demise is oddly appealing.
6) Playing Tyranids teaches you about your opponent. Though I have only used my tiny force a few times, there's something scientifc about it. Seeing how your opponent reacts to genestealers on the flank. When the Carnifex shrugs off hits and comes barreling at his commander. Etc.... Perhaps it's because I can get too attached to my other forces, but there's something pleasurable about expending units without giving a
7) ....which makes their named characters all the more intriguing. Like stories about Nelly the Loch Ness monster. Or "Brownie," the biggest gator in the pond. Humans have instinctively labeled other creatures to try to rationalize or understand them. "Old One Eye" is such a brilliant glimpse into the human psyche. You can hear the tone of almost reverence the old grey-bearded Sgt uses when he talks about how Old One Eye wiped out his unit.
8) You can't really them up modeling/painting wise. "Oh crap...that was the wrong arm? Oh well. This is a brand new strain."