Iron Sky is a fun, charming and casual game for the 360.
The 360 does not have many space combat games, so this is a rarity in of itself. Thankfully, the game does not take itself too seriously, and this is reflected in the story and gameplay.
You play as Top Gun-type of character - cocky in flight, cheesy one-liners and flirtatious with any women he encounters. The general story is basically an odd fan fiction: the Nazis survived WW2 by hiding on the moon and for the last several decades they have been building up their space fleet in order to invade Earth.
By the time they are ready Earth is basically united against the Nazi threat and sends several spacecraft to fight the threat together, after the Nazis reveal themselves by sending bombers and meteors against Earth. Your character is the US pilot there to show the watching Russian, Indian and Korean governments how it's done.
The game has less than 10 levels, each of which can take up to an hour to complete, minus the tutorial level. Throughout each level you will be intercepting Nazi sorties against Earth, escorting friendly ships to satellites and taking part in a LOT of dogfights.
There are also several optional side missions the player can choose to partake in for the Russian, Indian and Korean governments, while doing similar tasks for the US president.
The combat is very arcade and doesn't take much skill to master. All ships available function similarly, though the Australian Dundee ship is clearly the best for all tasks. There are several enemy types, ranging from quick and weak fighters to heavily-shielded and tankey bombers and even to enormous space zeppelins towing meteors.
The soundtrack is quite charming, though subtle. Every time you come out of light speed it seems like a copy of the Star Wars Imperial March is playing as you close in on your enemy, though it quickly changes before Disney could sue. The music amps up while in combat and nicely soothes when you're off on your own or refueling.
The biggest weakness of the game isn't the cheesy story or limited third-person perspective, it's the awful dialogue and acting. The dialogue is the cringiest, most overly cliche and quite misogynistic piece of writing I think I've seen in a game. Though the game deliberately doesn't take itself seriously, the dialogue, along with the C-rating acting, just goes a bit too far and drags on a few times when you're meant to be in the heat of a space dogfight or trying to launch a nuke at a meteor.
As for achievements, they're easy. You could probably finish the game in a day, though I wouldn't recommend it because the game is very easy to relax to and have a lot of fun with, so there's no rush. You'll get most achievements just for finishing the game. Just be sure to not leave the Korean fighter docked in the Korean space station, or it may void an achievement.