Is it worthwhile doing sidequests?

[rms]

I visited the machine village (after that crazy-hard circus boss fight, died many times!) and get a couple fetch quests, one to find a daughter (who I couldn't find in the whole highlighted desert area?!) and another to deliver supplies. These really struck me as running a long distance to quickly grab something then running a long distance back for a few small items.

Should I bother with these, or just stick with the main quest? Is there a list of recommended sidequests that are worth doing? (Mind you, I did like the visit itself to the machine village as it contributed to the world-building).

[TheSeek]

This game encourages exploration by not giving the player too much info, each sidequest has bits of lore and world building that, imho, are essential to enjoy the main story the best way possible(as example, the lost girl quest you're referring to gives some lore and info on machines and their relationships with each other).
Without spoilering, there are side quests that help understand, and sometimes even foreshadow, main plot points that will surface later on in the game, so my advice is to do all the sidequests you can before proceding witht he main ones.
There will be ones that you can't immediately complete in all their steps or for which you can't figure out where to go next because the related area hasn't been unlocked yet, and in that case it just means the quest can be completed later and with a more relaxed pace(i.e. can be started now, and completed days later when you just happen to be in or close to the area that the quest requires you to be in).

[Flux_Casey]

You'll get fast travel very soon after that point in the game. I'd hold off on getting into side quests until you've done that.

[TheSeek]

Originally posted by Flux_Casey:

You'll get fast travel very soon after that point in the game. I'd hold off on getting into side quests until you've done that.

You're obviously free to do that, but avoiding sidequests entirely and only doing them using fast travel once it's unlocked will most likely result in being underleveled later in the game

[Cacosubthree]

Side quests gives you extra exp. Without it, you'll be underleveled near the end. Moreover, you can get some weapons, pod programs and key items (like quality sachet that allows you to ride a boar or moose without a bait). And some of the side quest are fun. You must do that missing robot quest.

[rms]

Thanks all! I see your encouragement to do the sidequests, and I'm starting to embrace them. I'm at level ~18 now and in exploring frequently come up against level 25 or even 30, which seems odd; does the game expect me to visit these areas as part of later quests, does that happen often?

Also, on endings: I see mentions of A, B, C 'routes', will these be clearly pointed out as I continue? Also, I read some mentions of even more endings, will those be flagged in some way so I don't miss them?

[TheSeek]

Without knowing where you're at in the main story, it's hard to tell if you're underleveled or not, but if its the case(if everywhere you go enemies are 10 or more level above yours, you're most likely underleveled) just do more sidequest since that's exactly what helps being at the proper level to progress easily in the story.
In general, yes, you'll revisit many places more than once as part of different quests, but depending on the part of the main story you're at, enemies will be stronger than they were the first time you were there.

On routes and endings...there are 3 main routes, A, B and C, they're consecutive and as long as you watch all the end credits and continue playing even when the game is "finished" you can't miss them.
Each route takes to its ending, with route C leading to endings C or D depending on a final choice, but once ending C or D is unlocked, you will also unlock chapter select to change your final choice and see the other ending.
After you got all 4 main endings, you'll be able to unlock the final true ending E, for which you'll have to get ending C or D again, but...by the time you get there, you'll know how the game works on this so I won't spoil how to get it.
Other than this, there are other 21 endings(plus one exclusive to DLC), from F to Z, which are all joke/game over endings you'll get when you perform some specific tasks you're not supposed to, like leaving an area during a boss fight, getting too far from an urgent main quest, and so on.
The only exception is ending Y which is tied to "losing" to an optional boss you can only unlock by having all weapons at max level and finishing a specific side quest.

As a general advice, if you want to get all ending beside the main 5, i'd suggest checking the guides here on steam on how to do it.