The Guns are dead serious, the DD not so much. Still, a classic.
If you're into that 70-80s sf kind of movies, then I can recommend a few.
It was the time of dystopia flicks, it seems:
Rollerball(~1974?) - One of my favourites from the period. Corporate totalitarian regime rules the whole world using the "bread and circuses" approach. Rollerball is a sport that fills the role of "circuses" here. The story follows one player, who begins to realize the extent to which the society have given up it's liberties.
Can't say it's less fitting a commentary on a society now, than it was back then.
Don't mistake this one with the 2000-ish remake starring Jean Reno, and being generally terrible in every respect.
Soilent Green - Now, that's a classic. A rather simple story, and the twist is of the M.Night Shamalayan(or whatever his surname is) variety, but you can't really call yourself a sf film buff if you haven't seen it.
It's the future(that is, 1999 or something
), and the world can't sustain the exponentially growing populace. There is some algae-based food substitute rationed to everybody everywhere, and our hero is on track of some weird conspiracy involving the panglobal company producing the stuff(soilent green it's called).
Logan's Run - I remember only bits and pieces. A man awakes from a cryosleep, or something, to find himself in a society where everybody is young and beautiful. To be exact, everybody is younger than 30, and he soon finds out why. (not really a spoiler: they're offed afterwards)
Planet of Apes - What can I say. Forget the not-so-recent remake and see the real thing. A really good SF movie. Minimalistic, and not dumb, which is pretty much the oposite of the remake.
Death Race 2000 - Have you played Carmageddon? If yes, then you'll find out that the game was borrowing ideas(and even designs) from this movie like crazy. If not, then you'll find here a zany, half-serious bastard child of Mad Max and Wacky Races.
A Boy and his Dog - This one, in turn, is one of the major influences for Fallout. If you're a fan of the game, it's a must see.
I'm pretty sure that you must've seen Blade Runner, else you wouldn't call yourself a SF film lover, so I'm not going to try and sell it to you.
For the realistic-historical ones, try:
Stalingrad(1992) - the best (anti)war movie ever made period. The film follows a bunch of German soldiers, from when they are being shipped to join von Paulus' army, to the bitter end of said army.
Other good war/antiwar movies: Platoon, FMJ, Cross of Iron, Empire of the Sun, Grave of the Fireflies(animated).
Also, I recommend early Marlon Brando movies concerning the IIWW, like e.g."Young Lions". It's almost strange to see Germans portrayed simply as enemies, and not as faceless monsters of today's variety(cough, Private Ryan, cough).
There's this one film concerning reneissance era, which could be treated as historical, due to the amount of detail and thought that went into recreating people's mentality in that period. It's called "Flesh and Blood", starring Rutger Hauer, among others. The story concerns a band of mercenaries somewhere in Italy, as they are betrayed by their employer, and seek revenge. And how it bites them in the arse.
Too bad you haven't decided to post in
the last thread about movies instead, as it'd be generally better, IMO, to contain all such things in one place.