The trickiest achievement in this game to unlock is 'Once more, with feeling', which requires you to discover all of the bad endings in one playthrough. These endings are:

• Abandoning the hallway and fainting from hunger.
  
• Fainting after deciding not to eat today.
  
• Run away from the kitchen, but realise you've forgotten your keys.
  
• Spilling your oatmeal while cleaning the kitchen.
  
• Spilling your oatmeal while taste-testing it.
  
• Dropping the half-cooked oatmeal.
  
• The oatmeal overflows the mug it's being cooked in.
  
• Burn your hands on the cooked oatmeal, causing you to drop it.
  
• Cook the oatmeal, but realise you've forgotten your keys.

This guide will take you step-by-step through how to get all of these endings, and then successfully complete the game.

One important note before we begin; apart from the first one, each playthrough is begun by choosing [try again] from the previous playthrough's game over screen, and not by starting a brand new game!

Added requirement to get the new fifth achievement, 'Blow your nose' to the Playthrough One section

Just a few quick extra notes!

In the comments, some people have stated that following this guide has not unlocked 'Once more, with feeling' for them, though most have had it work for them. However, the very first comment from PeteOzzy says that it didn't unlock for him until he verified the game's cache, so if following every step in this guide does not unlock the achievement, please try his suggestion.

If it still isn't unlocking after that, then - while I hate being a pedant - you must be doing something wrong. If you skip a step on this guide, then I cannot guarantee that the achievement will unlock. The fact that so many people have commented saying that it does actually work for them clearly indicates the guide itself is correct, so I'm sorry I can't be much more help than that.

Also, PeteOzzy again with another comment that holding down Ctrl will skip through text, which can make this a lot faster!

• Start a new game
  
• [Erm, what do you mean by 'terrible']
  
• [Alright then, please carry on.]
  
• [Make up some excuse]
  
• Click on the tissue lying on the stuffed hedgehog
  
  
• [Blueberries and Cream]
  
• [Maple and Walnuts]
  
• [3 Packets]
  
• [1 Packet]
  
• [No, uhhhhh...]
  
• [What about the things?!]
  
• [Yes!]
  
• [Wait in your room longer.]
  
• [But...the hunger?]
  
• [Run away!]

• [No, uhhhhh...]
  
• [What about the things?!]
  
• [Yes!]
  
• [Wait in your room longer.]
  
• [One day without food isn't the worst.]

• [Yes! Go already.]
  
• [Move it lady.]
  
  
• [Run away!]

• [No, uhhhhh...]
  
• [What about the things?!]
  
• [Yes!]
  
• [Move it lady.]
  
• [Run away!]
  
• [Say hi]
  
• [Are you sure the kettle's on?]
  
• [Ask someone for help.]
  
• [You think so?]
  
• [Clean]

• [No, uhhhhh...]
  
• [What about the things?!]
  
• [Yes!]
  
• [Move it lady.]
  
• [Run away!]
  
• [Say hi]
  
• [Are you sure the kettle's on?]
  
• [Ask someone for help.]
  
• [You think so?]
  
• [Hide in the corner]

• [No, uhhhhh...]
  
• [What about the things?!]
  
• [Yes!]
  
• [Take it slow.]
  
• [Probably.]
  
• [Don't say anything]
  
• Don't choose an option and wait for the timer to run out
  
• Click twice on the oatmeal packets
  
• [Hide in the corner]
  
• Don't click through the text once the timer pops us, just wait for it to run out
  
• [Just eat it now!]

• [No, uhhhhh...]
  
• [What about the things?!]
  
• [Yes!]
  
• [Take it slow.]
  
• [Probably.]
  
• [Don't say anything]
  
• Don't choose an option and wait for the timer to run out
  
• Click twice on the oatmeal packets
  
• [Hide in the corner]
  
• Don't click through the text once the timer pops us, just wait for it to run out
  
• [Try the microwave?]
  
• [Just leave it alone.]

• [No, uhhhhh...]
  
• [What about the things?!]
  
• [Yes!]
  
• [Take it slow.]
  
• [Probably.]
  
• [Don't say anything]
  
• Don't choose an option and wait for the timer to run out
  
• Click twice on the oatmeal packets
  
• [Hide in the corner]
  
• Don't click through the text once the timer pops us, just wait for it to run out
  
• [Try the microwave?]
  
• [Stir it!]
  
• [Yep. Gotta cook it.]
  
• [Put it back in the microwave.]
  
• [Yes. Better safe than sorry!]
  
  
• [Just grab it and go!]

• [Yes! Go already.]
  
• [Take it slow.]
  
• [Probably.]
  
• [Don't say anything]
  
• Don't choose an option and wait for the timer to run out
  
• Click twice on the oatmeal packets
  
• [Hide in the corner]
  
• Don't click through the text once the timer pops us, just wait for it to run out
  
• [Try the microwave?]
  
• [Stir it!]
  
• [Yep. Gotta cook it.]
  
• [Put it back in the microwave.]
  
• [Yes. Better safe than sorry!]
  
• [Maybe use your shirt?]
  
• [Yes. Yes you should.]
  

• [No, uhhhhh...]
  
• [What about the things?!]
  
• [Yes!]
  
• [Take it slow.]
  
• [Probably.]
  
• [Don't say anything]
  
• Don't choose an option and wait for the timer to run out
  
• Click twice on the oatmeal packets
  
• [Hide in the corner]
  
• Don't click through the text once the timer pops us, just wait for it to run out
  
• [Try the microwave?]
  
• [Stir it!]
  
• [Yep. Gotta cook it.]
  
• [Put it back in the microwave.]
  
• [Yes. Better safe than sorry!]
  
• [Maybe use your shirt?]
  
• [Yes. Yes you should.]
  

A lot of credit for this guide has to go to hcbsmits for his post on the discussion boards, without which, I'd probably still be flailing blindly in trying to get 'Once more, with feeling'. Thanks also to everyone else who contributed to that thread!

Thanks also to PeteOzzy for his comment about verifying his game cache to get the achievement to unlock, and holding Ctrl to skip text quickly, which have now been incorporated into the guide proper!

Oh, and thanks to the developer, Samantha Browne, for dropping a comment on this guide. That really caught me by surprise!