With Takumi awakened and now completely aware of who (or should that be what?) he is, the climax of Chäos;HEAd deals simply with the "small" matter of him destroying Noah II to put an end to the delusions that have overtaken Shibuya.
Of course, as is so often the case with bad guys, it appears that the actual driving force of the head of N.O.Z.O.M.I., Norose, is rather more altruistic than it first seemed, as his goal is to keep Noah II out of the hands of politicans so that he can created a world where people (to put it simply) aren't mean to one another any more. Of course, wonderful though this concept is (and completely at odds with the rioting and the like we saw when Noah II was activated, but never mind - Perhaps the idea was for all the horrible people to kill each other), the philosophy that wins the day here is that a man who cannot choose ceases to be a man (to paraphrase A Clockwork Orange)... and quite right too.
So, much of this episode sees Norose and Takumi facing off, with the latter having to battle through and fight off countless delusions of being melted into a puddle and having a stake shoved up his... err, moving swiftly on... This use of delusions is pretty well in keeping with the series as a whole, so I suppose some kudos should be dished out for not going for an entirely action-based big finale to take us to the inevitable happy ending and a world restored to normality (aside from Takumi's delusional powers I assume).
While Chäos;HEAd can in no way claim to be a classic, it's turned out to be one of the solid shows of this season, mainly on the strength of its general concept of delusions, then delusions made into reality. The former offered up some fantastic early episodes where we really weren't sure what was real and what was fake, and although this power waned once the game was up and we understood the core tenets of the show, it still continued to be a solid and interested plot device that thankfully didn't descend into the realm of the deus ex machina half as much as it could potentially have done given the subject matter. The series also managed to avoid the harem anime possibilities that its character line-up gave room for, and created some reasonably well-rounded characters even if you didn't particularly like them all (with Takumi himself ripe to be the most unlikeable "hero" of 2008). Having not yet played the game around which this series is based, my thoughts on Chäos;HEAd are doubtless different from those who are familiar with it in its original form, but purely as an anime spectacle this show has managed to be a well realised and frequently intriguing work - In other words, I would imagine that it's accomplished everything that it set out to do.