It's recently come to my attention that some of the sidequests become locked and you can't start them at all if you don't start them by the time you finish the main campaign. As I'm likely not going to have the time to start a New Game+ anytime soon with all the fall new releases, I would like to finish all the sidequests before I finish the main story.
Which sidequests do I need to begin before the end of the main story? If you could put how/where I need to start them behind a spoiler too, that would be great.
Best Answer
Yahtzee is wrong; no sidequests need to be started before the end of the main storyline. The lead-ins to some sidequests disappear due to story events, such as Hot & Cold and Through the Looking Glass, but it's still possible to complete them.
One achievement is missable if you complete the sidequest where it can be completed, namely Catch.
Some sidequests are on timers and take a while to advance, particularly Shot in the Dark. Identity Thief can be done at any time after the first corpse is found, if you explore on your own; the feeder quests seem to only appear if there are no other sidequests in the vicinity. The Enigma Conundrum is also best started when it becomes available, after Batman visits the Steel Mill the first time, as the feeder quest for that takes a long while to appear.