I'm a big fan of the game obviously, and take this as a science whirl for you, most of the technology the humans use is completely plausible TODAY, bar the obvious FTL and Fusion Reactors and Space Ships. But that just enables the Sci-Fi aspect, otherwise its just supped up modern technology or half of it is well actually buildable right now, and this is a game set 500 years in the future. I like that in a way, it links me into the game, the first Halo was the game that i was first introduced too that hadn't been kinda given to me. I don't actually remember buying games i wanted till i really got into PC gaming, and the two/three games i enjoyed most on that was Halo 1, Crysis and Total War series.
I did go into the extended universe and was quite peeved with Reach but i worked around it in my mind only thing i cant work around is the last mission and why they felt to make it Cortana and the Pillar of Autumn, could have just been an important data cache she gave them which they had to get to (Insert Ship Name Here) but i guess Cortana and Autumn give long time Halo fans an investment to complete the objective. As well as this i see Halo being compared a lot to games that are more RPG then shooter. Okay of course an RPG is going to have in game a more fleshed out story, why the hell do you think its an RPG, again its a Shooter so the depth of story it has is pretty damn good, considering most other games that are not an RPG have really terrible stories comparatively.
I really really like Halo as a series, i wasn't completely put off with Halo 4 when i was going in expecting to be completely disappointed with it, i strangely enough understood the plot and didn't have to read the latest novels to understand everything that was going on. I guess i just enjoy the story, the multiplayer the single player. I've been told that i missed out on a lot with the Quake series etc, but i have to agree i prefer the way it is now, before where was he hiding all the weapons in his arse? I'm sorry but that sort of thing completely throws me out of the game, it breaks my immersion. I'm not saying i like CoD games either, where the odd grunt can carry equipment that two or three men only could carry, but a super soldier in a experimental armour that can enhance his strength etc. and that is plausible you could carry two heavy weapons.