OneShot

If you want to play this game without a walkthrough or spoilers, but don't want to miss any of the achievements, this guide is for you. I've done my best to keep the information in this guide to a minimum. However, if you're looking for a more detailed guide, I recommend this OneShot achievement guide by warpsoul. It does great job explaining which actions you need to take in each area before moving on to the next.

Here's a brief overview of all achievements, in the order that you need to know about them:

"Oneshot" requires you to complete the game without clicking the X in the top-right corner of the game's window. You are only allowed to do this once, in the tower near the end of the game.

"Chaotic Evil" and possibly "Shock" should be unlocked in the Barrens (1st area) before taking the boat to the Glen (2nd area), although the latter achievement can also be unlocked later.

"Ram Whisperer" requires you to complete the ram puzzle in the Glen (2nd area), without ringing the bell to reset the rams' positions. Watch this video by Govo Bird:

"Extreme Bartering" requires you to interact with the trader in the Glen (2nd area), and attempt to trade with every item that is possible to obtain up to this point. When trading the wool with the trader, do not accept his first offer of only the bottle of dye. Instead, accept the second offer that includes the novelty T-shirt. Also, do not combine the bottle of dye with a certain other item before attempting to trade the bottle of dye with the trader. The full list of items is:

"Secret" requires you to obtain the novelty T-shirt from the trader in the Glen (2nd area) and use it later in the Refuge (3rd area) before entering the tower.

"Rebirth" requires you to obtain two items in the Glen (2nd area) and use them later in the Refuge (3rd area) before entering the tower. These items are the tube of water (obtained in the research station) and seed (obtained from Maize). Use them somewhere in the Refuge before entering the tower. If needed, you can refill the tube of water in a handful of places in the Refuge.

No other achievements have to be unlocked in the Glen (2nd area) before entering the cave that leads to the Refuge (3rd area).

"We Ride at Dawn", "Bookworm" and "Pancakes" should be unlocked in the Refuge (3rd area) before the entering the tower.

"Return" can be unlocked after completing the main game, you need to figure out how to trigger New Game Plus.

No other achievements have to be unlocked in New Game Plus.