I will start this guide from here as it's the part I get when I click on continue, the four previous puzzles were pretty easy as you only had to reproduce the puzzle that were shown.

First you will have to get in the train, mind the gap.

As soon as you arrive, grab the gun from the broken fortune telling machine and proceed to continue.

You encounter Seren, she is protected with a shield and you are unable to press the button.
You will have to ring the bells in order to force your way in.

On the left side you will have to shoot the bells in this order:
2 5 1 4 3 (1 is the bell on the middle)
And on the right side:
1 3 5 2 4 (1 is the bell on the far left)
Alternate order (if the previous one didn't worked):
Left side 3 1 5 4 2 | Right side 1 4 2 5 3

Finally press the button and she will throw you on the floor.
Grab that axe and start to destroy the generators.
Be careful, avoid the electric current after destroying some generator by jumping on the green circuit board.

Then go for the coil.
At this point you have the choice to continue or exit and get the alternate ending.

See "MASTER REBOOT - Find the alternative ending" below

If you choose to continue just proceed to the warpgate that appear just behind her.

From here you can just run and jump, these obstacles are pretty easy to overcome.
After that, you will have to beat Kali, fortunately Seren come to help you and distract Kali while you will have to destroy five orbs. Again there will be some obstacles, only the jumping one can be a little annoying.

See "THE FINAL COUNTDOWN - Complete the Final Level in record time" below


Congratulation, you just finished Master Reboot, you should have received an achievement for completing the game.

Now replay the last part to get the achievement below.

After destroying the coil, you have the choice to continue or exit and get the alternate ending.

If you choose to exit, you only have to press esc and click on exit the soulcloud.

Your screen if you set the Welsh as default language, for WELSH WIZARD achievement.

You will see another cinematic and receive the achievement.

To unlock this achievement you have to complete the lastest part which is timed in a record time.
I got the achievement with around 64 seconds left, so just try to aim for the fastest time (from a comment, 31 seconds left is fine).

For this one you just have to change the language to Welsh and complete the game.
You can change the language then just click on continue to play the last level again, there's no need to play the entire game again in Welsh

Playground Puzzle
To get the yellow pie, you have to find the yellow triangle near a tree at the start then find the tree with a drawn yellow triangle and a crow, press use on it.

Graveyard Puzzle
7147

Library Puzzle
RED > 3 letters
BLUE > 4 letters
GREEN > 5 letters

Oddly I managed to complete it in another way.
They were 3 red switches > 3 red things
The generator was blue and the 3 switches > 4 blue things
The walls and the celling were green > 5 green things