suggestions for 18 yr old male: sci fi and fantasy?

Anyone know of any good science fiction, fantasy, apocalytic, or possibly horror types of books for a 18 year old guy which are not extremely popular (and hence often mentioned), but are well known enough to likely be at libraries and bookstores? Adult, YA, or even juvenile fiction is acceptible.

He (my brother; yes, I am my bro's source for any literature he's ever going to read) is into strategic war types of games, so if anyone knows interesting war-type of novels, those might be good... He also prefers modern day, futuristic, or alternate reality books; which is to say he doesn't like historical books set before the 1800s or so. He also isn't into romance, but if there's a book in which romance is a subtheme, he might not mind that.

Thanks for all the help in advance!

He might like the Artemis Fowl books by Eoin Colfer.

Ender's Game or Only you can save Mankind might be worth a look

Virtual War by Gloria Skurzynski is a good one. And it has a couple of sequels.

the Vorkosigan series by Lois McMaster Bujold is a great space opera type series. Lots of great characters and enough books to keep a reader busy for a while.

I second the Vorkosigan series - I just read through those recently and found myself thinking it would have been something I would have enjoyed when I was a teenager.

Also these are probably too popular for what you're after but it sounds like he would probably like (none of the author touchstones are working for me right now, urg, so I'll mention books as well) Iain M. Banks (The Wasp Factory), Philip K. Dick (the Bladerunner/ Do Androids Dream of Electric Sheep guy), and my favorite, good old Kurt Vonnegut (I love Breakfast of Champions but he might be more into Cat's Cradle, Slaughterhouse-5 etc.

Definitely second Ender's Game - battle tactics and mind games galore, and really riveting.
What about George R. R. Martin's A Song of Ice and Fire series, starting with Game of Thrones, or Lies of Locke Lamora by Scott Lynch (has sequels), or The Name of the Wind by Patrick Rothfuss? (Sorry if these are often mentioned!) Or the Tamir Triad by Lynn Flewelling, starting with The Bone Doll's Twin...
And one of my favourite series is Megan Whalen Turner's The Queen's Thief, starting with The Thief, but this is aimed at a slightly younger audience than the previously mentioned books.

You might want to check out this thread in the FantasyFans group if you've not seen it, AraKnid.
It's about military fantasy recommendations, so there's a fair amount of overlap with the books mentioned here.

http://www.librarything.com/topic/33079

(As for ideas of my own, I'm afraid I haven't any. ^-^; )

Thanks for all the suggestions! My brother has read Ender's Game, Artemis Fowl, Virtual War, and Name of the Wind, and sadly he isn't very inclined to reread books unless he's completely forgotten them (which is possible with some of these). All the other suggestions look really good, and I'm reserving them from the public library, which has all of them except Wasp Factory. Also, thanks for the suggestion, Shanra; I'll be sure to look through that thread!

I didn't realize The Lies of Locke Lamora had sequels... I'll have to look into those myself :)

Neal Stephenson's Snow Crash and The Diamond Age. I'd start with Snow Crash.

Robert Heinlein, particularly The Moon is a Harsh Mistress, Stranger in a Strange Land, Double Star, Starship Troopers. Notice that Starship Troopers, the book, is a completely different matter than Starship Troopers, the movie. Almost anything Heinlein ever wrote is worth reading, but some are better than others.

If he hasn't read Dune, he should. He might like some of the sequels and prequels as well. But Dune is one of those books that everyone who likes SF ought to read.

The Pelbar series (the first one is called The Breaking of Northwall) is an excellent fantasy/post-apocalyptic series.

I'd also recommend His Majesty's Dragon which is the first of another series despite him not liking historical books, because it fits your other descriptions so well and my 18 year old brother (who sounds rather similar to yours in book taste) enjoyed it. It's an alternate reality, in which the Napoleonic Wars are being fought with dragons.

Anything by Brandon Sanderson is also amazing fantasy, Elantris is a stand alone book and Mistborn is a great trilogy of his.

Maybe Leviathan by Scott Westerfeld? It's a steampunk alternate history of the lead-up to WWI.

The Emberverse series by S.M. Stirling might be good for him. Its a post apocalyptic storyline where *something* happens and suddenly there's no electricity, gunpowder doesn't work, no steam power... etc. Basically the human race is plunged back a few hundred years where everything has to be done by hand and knowing how to use a sword and bow is imperative to survival. I have a love hate relationship with this series because it requires a little too much suspension of disbelief at times... but heck the guy can write a really good battle scene.