Since the fist Act follows the story of Justin and Kloot almost separately, as in you can't transfer items between them, I was able to split the two paths into two walkthroughs. However, note that there's a small (but significant) part where Justin was able to influence the robot QP-43 in Kloot's current timeline. This is why the "almost" is emphasized here :)




How to set up the rabbit trap?
Note the specific type of stick you'll need and how you'd need to assemble the trap - the net with the carrot, and the twig with the vine.

1. How to get the fuel for the flamethrower?
You can get it from an abandoned car.

(SPOILER ALERT! If you want to try figure out the solution for yourself, DON'T read on! )
Use the bellows on the abandoned car outside the abandoned robot factory in the future to get fuel. Once the bellows is full, use it on the flamethrower to transfer the fuel over.

How to get QP-40 to spill the beans?
The can needs to be used by the right man.

(SPOILER ALERT! If you want to try figure out the solution for yourself, DON'T read on! )
Get Kloot to use the bug spray on QP-40 and then the robot will mention something about being ready to spill the beans to his beloved, Julia. So, you'll want to get Julia to get the robot to start talking.

A work in progress!

You should be able to get most of the achievements simply by following through with the story, but there are some that you might miss depending on when you approach a character and what you did.

Here are the few that I've found that I reckon you might miss:

You can get a chicken trophy by walking away from the portal while playing as Justin at the very beginning of the game.

You can also get another trophy by walking into the hospital in the future and walking right back out.

When you enter the robot factory, exit the factory immediately and make sure you don’t press the red button to get a trophy.

In the cave underground in the last act, click on the banana peel on the edge of the cliff.

While at the Office, click on the laptop with the bunch of green text on them. Choose the North (N) option and then proceed to slay the troll.

Once you're done with the Troll-Slayer achievement, don't pick up the broken mirror. Instead, head West (W). Talk to the chicken and you'll have a sudden realization that you're a player. This will then get you this achievement.

Very important: Make sure to do this before helping Justin's cavefolk ancestor!!!

Head to the All-is-Well Playground and ring the bell to start the bike race. If you do this before helping Justin's cavefolk ancestor, you'll be able to get to this achievement. You won't be able to get this achievement if you help the ancestor first, however.

This one's easy and can be done at any time. Simply pop the snot bubble on the sleeping cavefolk at the cavefolk daycare at least 3 times (in a row) to get this.

Go to the Willow in the Past and head to A Place in the Shade among the hedges. Here, you can choose how long to meditate. To get this achievement, you'll need to pick the 10-minute option.

However, be prepared: you actually will have to stick with it for 10 minutes. Best go grab a cuppa or something :) For me, I took a power nap... haha.

Make sure not to put the rock in the hole near to the dodo if you want to get this achievement. Do everything you'll usually do to get produce the loud noise to get the dodo to hide its head in the hole. If the rock isn't there, you should get this achievement.

During your session with the psychotherapist, when he asked you to lie down on the divan, refused and choose to stand to get this achievement.

Save sushi in the final act. All you need to do is to get Julia to pour some water down the sink and get Justin to catch the water in the fishbowl. Place Sushi in the fishbowl and you'll get the achievement.

(WIP) I suspect you need to get all the Trophies of Cowardice in a single playthrough to get this achievement.