The lights are on
(As with all of my guides, this guide will be periodically updated and moderated as need be. Considering nothing new concerning Bastion has released, once I have talked about all of the achievements- I will only continue to write about either about walkthroughs for each or other information concerning them. Last Updated: June 19th 2012.)
Mind you- as usual, I will warn you of spoilers or the possibilities of spoilers ahead with vibrant colors highlighting any achievements that are secret achievements or otherwise may ruin most of the game for you. If you do not care either way and simply want the achievements, then feel free to read on!
Full Achievements List for Bastion (Xbox 360):
1) The End: This achievement can only be earned by choosing to avert the almighty Calamity at the end of Bastion- not the end of New Game Plus or any other modes, although it can be earned in NGP if it wasn't previously earned somehow.
2) Pet Sitter: In order to gain this achievement- which you do not get in one playthrough always, as you can screw it up- collect all relevant items in relation to bosses and the eggs and such, then they should appear in the Bastion. Possible pets that work for the achievement include: Squirt, Steam bull, Anklegator, Windbag, Raptor nest, etc.
3) Vigilante: To earn this achievement you must collect 12 vigils or 50% of them, also- be sure to properly click on them after you have beat them and to get bonuses for equipment, abilities, etc.
4) Altruist: Complete every single vigil challenge up to 100% and on every single one of the levels that it requires as well. Pretty self explanatory. Beware though, because if you encounter a glitch you must either save and restart your Xbox or attempt the challenge once again.
5) Calamity Kid: Simply beat the game one more time, but this time be sure to play it in New Game Plus instead of simply restarting from the beginning.
6) Mind Voyager: To earn this achievement you must complete all three Who Knows Where challenges, although there is also a secret fourth- this one is not required and does not count towards the achievement as well. The three needed are the smoking pot, food, and sleeping bag.
7) Kid at Arms: To earn this achievement, you must upgrade all eleven weapons at least once in the game. The weapons are all easily found in-game and throughout the levels and the world, but here is a complete list of all eleven anyway: Army combine, Breaker's Bow, Brusher's Pike, Cael Hammer, Calamity Cannon, Dueling Pistols, Fang Repeater, Flame Bellows, Galleon Mortar, Scrap Musket, and the War Machete.
8) The Stranger: After you pick up the core near to the ending bit of the level, hurry on your way through the collapsing segment of the level in order to reach the portal and warp your way to Skyway. At the end of the level, you will earn this achievement for completing the Wharf District and the level.
9) The Ura: Complete Zulf's Who Knows Where challenge and stop him from assaulting the Bastion with his other survivor buddies in order to earn this achievement. The achievement is effectively given out once you halt the siege upon the Bastion.
10) The Survivor: Once you complete the Hanging Gardens level and discover the survivor of the Calamity there- Zulf, then you should earn this achievement. It's not too terribly much of a secret once you get it of course, as there should be no way to miss it due to the fact that it is story related as well.
11) The Singer: Finish the Prosper Bluff level and then speak with the singer- Zia, once she has traveled from the same cooking pot used for her Who Knows Where challenge. Once she arrives at the Bastion, you can also pick up gramophone and play music there as well. Talk to her in order to receive this achievement easily.
12) The Beginning: This achievement can easily be cheated instead of having to complete the game twice to get, as if you choose the "stay in calamity times" choice at the end of the game- you will receive this achievement. Note: If you don't replay from those last moments again, you won't receive the "The End" achievement unless you already have it, then that is no big deal... You get this achievement as soon as you choose the second choice and also get to watch the second ending.
(The only thing that has really been updated at the moment is the addition of a cover picture of sorts for Bastion. Also, note that- across all of the guides I have or ever will create/created, I will try to update them all at once every few days, weeks, or months or so... Thanks again. 6/19/12.)