This guide is performed through basic "Go there, do that" and does not include detail description of every single step. But it should provide all necessary information for easy playtrough. However if you stuck somewhere or feel that some part of guide should be more detailed or include explanatory screenshot - please comment and I'll do my best to improve it.
I've also decided to exclude all founded Easter Eggs from the main walkthrough and put them in separate section at the end, so to not spoil fun for those who wants to find them themselves or don't interested in that sort of things. But to ease your hunt I'll mark that place in the walkthrough with [EE] abbreviation to give you a hint that it's about time to look around or skip to the "Easter Egg" section.

This is a categorized preview of all achievements, you’ll get the detailed version (if needed) during the walkthrough.
Storyline
You’ll get them automatically when you progress through the story

• A New Dimension – after Shifting In shadow for the first time
  
• Room 529 – after leaving the Cabaret
  
• You Broke My Finger! – after leaving the Cinema
  
• A Carousel Of Broken Dreams – after finishing Act I
  
• This Circus Is A Disaster! – after leaving the circus tent
  
• Handy Person – after repairing three attractions
  
• How’d You Get In? – after completing the Workshop
  
• Let There Be Light – after completing the Lighthouse
  
• FIN – after completing the game

Collectible
You need to collect something to get them

• Illuminated – after getting two luminaries
  
• Streets Sweeper – after getting all Collectibles in Act I
  
• GroundsKeeper – after getting all Collectibles in Act II
  
• The Cyclops' Bottle – after picking up bottle at the Carousel area
  
• BookKeeper– after getting all Collectibles in Act III

Note: there is no achievement for getting all of the luminaries, you only need few to proceed in some points.
Action
You need to do something to get them

• Not That Kind Of Game! – after walking up the door with the “Dirty” sign to the left of the Cabaret
  
• To The Heroes Among Us – after activating hidden Extra Life 2012 Logo
  
• My God, It's Full Of Stars! – after falling in the void on the way to the Cinema
  
• Punching Bag – after letting gangsters to beat up Johnny
  
• The Family Life – after interacting with Didi’s family pictures without skipping cutscene
  
• No Backpack Bird Needed – after jumping in the chest on the Pirate Ship

Special Conditions
You need to succeed in something on your first try. It’ll be explained how to get them during walkthrough

• Now That’s Thinking With Shadows – after getting over the void on the first try
  
• Just Like Harry – after getting over crocodiles on the first try

10 Luminaries, 10 Collectibles, 11 Achievements
Get Collectible “Didi’s drawing“ (1). Jump out the window, Shift In [“A New Dimension” Achievement; 1] and go down, move the ash cart. Go in shadow to the balcony. Get the Luminary (1) in the room. Walk down the stairs and turn right – get Collectible “Kat's Poster” (2). Go across the street and go by the shadow of a bicycle to the Luminary (2). [“Illuminated” Achievement; 2] Go further down the street and pick up Collectible “Newspaper” (3) from a table to your right. Go to Didi and follow her in. Turn the lights on to the right of the door - aim two spotlights on shadowy musicians – go on a second floor by the shadow of either musician - pick up Collectible “Notice about Didi” (4) on one of the tables. Aim last spotlight. Go through the door and under the staircase – pick up Collectible “Johnny’s Check” (5) from the floor. Go out and down the long alley. [“Room 529” Achievement; 3] Turn right and go to the door under neon sign “Dirty” – get Achievement “Not That Kind Of Game” (4). Go to Didi across the street and get Dash ability. But before breaking wall and going further let’s have a look around and pick up all that left. First let’s go down the main street where there is a floating image of gramophone. There is a wooden wall to the left of it – test your new ability and Dash through it – pick up Luminary (3). Activate Memory (I’m not sure how to call that, so I’ll use term Memory further on) by walking up to gramophone image and get up on the balcony by appeared shadow scene – pick up Luminary (4). Jump down from the balcony, but not on the street – on the other side of the gate. Go in the room upstairs and activate the light – you’ll get “To The Heroes Among Us” Achievement (5).
Now get back to Didi and follow her in the pub – pick up Collectible “Vincenzo poster” (6) on a table. Move the light cart so shadows will look as something like that. Go up on the second floor and out on the balcony. Go by catwalks, then shadow-walk in the light on the wall to another catwalk and pick up Luminary (5). Go inside and pick up Luminary (6), Collectible “Newspaper” (7) and Reel (in that order). Go back on the balcony and jump down to Didi – follow her and fix light. Cross gap by Shadow-walking by first billboard, jumping at the end (which cause you to Shift Out) and Shifting In on a second billboard. Now, to get Achievement “Now That's Thinking With Shadows” (6) you need to cross gap on your first try. If you’ll fall down – go in the Menu – Restart from the last save – and you’ll be in the room where we picked up Reel (if you picked up objects in different order than check room if there is Luminary left). Go to the gap and try again. Repeat until you’ll get on the other side or change your mind about getting that damn achievement. If you somehow managed to not fall even once – than just jump down yourself (only after you reached other side, so you won’t have to do all that jumping jazz again) to get “My God, It's Full Of Stars!” Achievement (7). Then break supporting walls behind billboards and go to the cinema. [EE] Pick up Collectible “Closing Note” (8) from ticket window. Go to the door and follow Didi inside. Move the figures in any position that’ll help you climb up by theirs shadows (this is just an example, you can place them more convenient). On the second floor pick up Collectibles “Prison release” (9) and go through the doors by Shifting In on one side and Shifting Out on the other. [EE] Go downstairs. Wait a little till you get “Punching Bag” Achievement (8), then go inside the film cabin by Shifting In and Out again and interact with projector. Follow Didi out. [“You Broke My Finger!” Achievement; 9] Get Luminary (7) (close right umbrella, wait a little – close left umbrella, jump on shadow of a sign, wait for left umbrella to pop open, jump on its shadow – quickly jump on the left shadow and over left umbrella until it’ll pop open and go to the balcony). Dash through the wooden wall.
Go back across the billboard bridge and further down the main street to the “EXCELSIOR” neon sign. Turn left from hotel and activate Microphone-form Memory – get Luminary (8) (jump on the hand, then on the head, then take a drive on the shoes to the balcony). Go in the hotel. After cutscene turn back and pick up Collectible “Johnny’s notebook” (10). [“Streets Sweeper” Achievement; 10] Go to the elevators and push the cart in the left elevator. Get on the left elevator by jumping twice – first Dawn will grab the edge and then she’ll pull herself up. Get on the second floor the same way. Call the elevator and go on the other side of the floor – interact with two mechanisms to position shadows into something like that. Jump by shadows on the third floor. Find an open door and go downstairs to pick up Luminary (9) and open door to the second floor (so if you’ll mess up later you’ll be able to walk up stairs and not jumping again). Call the elevator on the third floor and activate fire alarm – go on the other side and jump on the left shadow that moving up and from there on the small platform with the Luminary (10). Jump and pull yourself on the fifth floor. Go through the door and Dash through two wooden walls. Out on the balcony, go by planks and quickly Shift In until they fall down. Stand on Kat’s shoe and wait till she’ll move you up on the piano – stand on cigarette and wait till Kat will move you up – jump on her head and wait till Johnny reach his arm – go by his arm and on his head and wait till he’ll move his hat over to the balcony – jump on balcony and Shift Out. Now, if you want to give yourself food for thought about meaning of this whole shadow world – go in the door and then back to the balcony and watch the whole shadow scene. Then go through the door again, down the stairs and let Didi in. Follow her on balcony and watch the scene again but with differences. [“A Carousel Of Broken Dreams” Achievement; 11]

15 Luminaries, 6 Collectibles, 7 Achievements
Pick up Collectible “Johnny’s portrait” (1) on the table. Interact with the photo in the hallway – don’t skip the cutscene to get “The Family Life” Achievement (1). Interact with “Eviction Notice” downstairs, interact with it again after cutscene to get it as Collectible (2), pick up another Collectible “Kat’s letter” (3) on the table. Go out. Follow Didi’s instruction and go on the other side with new Shadow-Dash ability. Follow her into the circus tent. [“This Circus Is A Disaster!” Achievement; 2]
Go behind the curtains and pick up Luminary (1) and Collectible “Photo of Didi and Kat” (4) (in that order). Left the tent and go over suspension bridge, then down the stairs and turn right, where glows sign “CHIAROSCURO”. Go in and reach the stage. Pick up the princess hat, Shadow In and enjoy the story. First Adventure - do a lot of jumping in 2D side-scrolling platformer style until you’ll reach crocodiles. Now, to get “Just Like Harry” Achievement (3) you need to get on the other side on your first try. It’s not hard (especially in comparison with previous billboard jumping), but if you’ll fail – not to worry, just as before – go in Menu - Restart from the last save – and repeat your way starting with circus tent. Just check the backstage before leaving it in case you’ve mixed up the order in first place and now there is a lonely Luminary left waiting for you. When you’ve done with crocodiles there will be more jumping and Mushroom puzzle – you need to activate mushroom to the right, make a pause and activate mushroom in the middle – jump on the left lower branch and when it’ll go up it’ll throw you on the right brunch, from where you’ll quickly jump on the next tree. And now we meet the Ogre. Jump on stump and when Ogre will raise his club – jump back. Club will stuck in the stump and you can run up by Ogre on the other side. Jump up when Ogre will start his club movement, so you’ll land on the club – run up by the Ogre once again and wait till the tree will crush him. Jump on it and free Fred. Second adventure – run to the right until you’ll reach the abyss with spikes – listen Johnny’s and Didi’s dialogue – Shift Out, pick up the umbrella and Shift In – run, jump and carefully navigate your fly to avoid spikes. After landing in the cobweb jump couple times and break free. Run, break free from more cobwebs, hide under the ledge from boulder, and run from Giant Spider. Try jump over cobwebs, since Spider is quite fast and very deadly. Some jumping later you’ll break two cobwebs and crush Spider with a boulder to everyone’s joy. Free poor Fred and watch him go on the third Adventure. More jumping and avoiding rolling boulders and we meet the Dragon. Get close to tease him and jump back, so he’ll burn Fred’s ropes. Do this three times and you’ll get your set of a brave knight and happily ever after. And you’ve successfully fixed one of attractions.
Now exit stage area and activate another Memory image in form of Reel that was in front of the entrance – make your way to the balcony and pick up Luminary (2).
Go through the archway to the Horse Carousel area. Pick up Luminary (3) behind the carousel and charge the control switch. Jump on the Horse Shadow and jump your way in the direction opposite to the motion of the horses. With some jumping and Shadow Dashing you’ll get to the roof overhang with Luminary (4). Jump on the billboard and continue your horse jumping to the balcony. Walk by the Didi’s stick shadow and another roof overhang, pick up Luminary (5) and jump over on carousel’s roof and fix the beacon. Jump back to the roof overhang and jump and Shadow Dash your way by the stars and comets till you’ll reach the catwalks over billboard. Jump and pull up on the balcony and pick up Luminary (6). Shadow-walk on the rooftop, jump on the balcony, more shadow-walking and you’ve finally reached required roof. On one of the tables of the rooftop cafe is a bottle – pick it up and get “The Cyclops' Bottle” Achievement (4). Pick up Luminary (7) under the stairs. Go upstairs and untie balloon. Second attraction is fixed.
Go past the tent, there will be shadows of floating rocks on the wall. Jump and Dash to the doorstep and pick up Luminary (8).
Go down the stairs on the quay. There is a “Test your strength” attraction, use its shadow to reach balcony with Luminary (9). Enter the “Tortuga's Revenge” ship. Pick up Collectible “Maintenance note” (5) to the left. Pick up box - Shift In - go to the right, drop the box, jump on it – jump, Shift Out and grab the edge, pull yourself up. Lower the bridge, get back and pick up the box again – cross the bridge and put the box on the red button. Enter wheelhouse by the old Shift In-Shift Out trick and turn the steering wheel to the full. Go to the shadow of the wheel and ride it to the upper platform. Pick up Luminary (10) from the platform above wheelhouse and grab the box – Shadow In, ride the wheel to the lower platform, Shift Out and drop the box on the green button. Pick up the last box, bring it in the wheelhouse and drop on the purple button. Go through the opened gate, pick up Luminary (11) and join Didi in the boat. After the ride jump into the opening-closing chest to get “No Backpack Bird Needed” Achievement (5). Go up the ramp, shoot a canon and jump back down. Go to the boxes, jump on top of them, jump on the shadow of the tentacle, let it lift you up and jump on the platform. Go in small cabin, interact with the door, grab the cannonball and shadow-walk on the other side, put the shadow of the cannonball under the shadow of mechanical claw and shoot again. Go back to the platform where we get the cannonball and jump down the hanging boat with Luminary (12). Get back in the Didi’s boat. Enjoy the ride to the next area. Go down, pick up cannonball, go all the way around by the ramp. Shift In at the end, and place the shadowy cannonball in the middle of the lower part of a shadow platform. Go back to the mechanism in the middle of the ramp route and raise the shadowy platform with the cannonball – pick it up again and go charge the cannon. Pick up Luminary (13). Jump down and charge the door lock with three luminaries. Follow Didi and go down one flight of stairs – jump down under the stairs and pick up Luminary (14). Go further and pick up another Luminary (15) to the right. Go further and pick up Collectible “Book” (6). [“GroundsKeeper” Achievement; 6] Pull the levers at the same time with Didi. [“Handy Person” Achievement; 7] Get back in the tent.

4 Luminaries, 10 Collectibles, 4 Achievements. Note: in this act Collectibles doesn’t encounter in the order they shows in the showcase
Follow Didi until you are at the entrance to the workshop. Pick up Luminary (1) to the right of the workshop behind the café table. Go up the stairs opposite workshop – pick up Luminary (2) at the end of the street. On your way back go down the arch to the left and pick up Luminary (3). Go back, walk past workshop to the Gun-form Memory, activate it and pick up Luminary (4).
Go inside and charge the control desk with luminaries. Turn the mechanism until shadows are in the pictured below positions. Pick up cannonball and put his shadow as pictured. Run back to the control desk and turn mechanism so it’ll carry the cannonball on the balcony. Go through the door to the mechanical orchestra – jump on the broken stairs – pick up the cannonball and put it in the mechanism. Jump by the shadows of the mechanical orchestra on the balcony. Jump down in the museum. [EE] Pick up Collectible “Science Picture” (1). Move the light cart, so the shadows placed as pictured. Use the gap in the gear and ride in it on the other side, more jumping, shifting and dashing will bring you on the balcony with Solar Machine Elevation Reset. Interact with it and jump down. In the other part of the museum reach the balcony by jumping on the janitor’s shadow. Go down the stairs and pick up Collectible “Science Picture” (2) from the wall. Open two doors (so you’ll have a shortcut if you’ll fall somewhere). Go up another stairs and out on the balcony. By the wall to your left shadow-walk and –dash to the clock. Go through it and pick up Collectible “Newspaper” (3). Go further and watch the cutscene. [“How’d You Get In?” Achievement; 1] Go to the stage.
Go to the lighthouse. [EE] Go through the glass by Shifting In and Out. Turn on the lights on the switchboard to the left. Interact with the spotlight to direct it on the box. Jump to the box and shift it in shadow. Jump back and carefully move the spotlight with the box within on the floor to the left. Drop the box by moving light through the crack on the wall and direct the light back on the ball. Jump to the box, pick it up, carry it to the button and drop. Go up the stairs and reach the platform with another box by shadow-going inside the moving light. Pick up the box and continue your shadow walk to the next platform. Drop the box on the button. Go up the stairs and take the Collectible “Photo” (4) off the wall. Turn on the switch and go upstairs. Pick up Collectibles “Lecture Note” (5) from the floor and “Newspaper” (6) [EE] from the box. Turn on the switch and quickly Shadow-Dash to the platform. Pick up Collectible “Photos” (7) from the box, go upstairs and pick up two more Collectibles “Science Pictures” (8,9). Open the light beam near the stairs and jump your way by either of the gears to the next floor. Pick up the last Collectible “Picture” (10). [“BookKeeper” Achievement; 2] Go outside the hole in the wall and go to the left. Pick up the box and place it against the wall. Go inside and open the second light beam. Shift the box in shadow and interact with the spotlight. Focus it on the shadow-box and carry the box to the catwalks above. Direct the light on the ball. Make your way to the box and place its shadow near rotating wall. Carefully carry box across the rotating wall on the other side and drop. Focus light on the ball. Pick up the box, bring it inside and drop on the button. Go outside, jump right onto the wall and Shift In, so you’ll be standing on the shadow of the pipes. Jump on the shadow of rotating beam and run to the stirs. Go up. Use all your learned jumping-shifting-dashing skills to make your way to the top. Turn on the light and direct it on the stage. [“Let There Be Light” Achievement; 3] Enjoy the show. [“FIN” Achievement; 4] Enjoy the completion of the game.

All this Easter Eggs can be found during the game
Act I
1. TARDIS from "Doctor Who" show. When you've crossed the gap before entering the Cinema turn right. You can see it through the gates.
2. "Fight Club". On the second floor of the Cinema.
Act III
Grand Easter Egg Collection. In the Workshop, in museum area. Just look around.
3. "Back to the Future". Doc Brown's "not to scale or painted" model of a Hill Valley.
4. "Terminator 2: Judgment Day". T-800's robotic arm.
5. "LOST" show. From a certain perspective you can see a DHARMA logo.
6-7. "Star Trek" & "Star Wars". The warp core of USS Enterprise (NCC-1701-D) from "Star Trek" and Anakin's lightsaber from "Star Wars"
8. "Lost Orbit". Harrison from the Lost Orbit game by PixelNAUTS studio, who also did environmental art for "Contrast".
9. "Contrast". I'm not sure that I've got it right or if it counts as an Easter Egg when it refers to the game itself, but I just thought that this tower looks like the Lighthouse (next locations after the Workshop)

10. "Dark City". "Shell Beach" postcard. Behind the Lighthouse on the table.
11. "Sherlock Holmes". The newspaper article (Act III, Collectible 6).
Thanks to detective skills @Snow we've got this reverence to sir Arthur Conan Doyle and his Sherlock Holmes world.








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I might also add Achievement references later and substitute reference images on the other ones with better resolution, but for now that's it.
Oh, and of course you are more than welcome to share your discoveries!

I hope this guide was useful for you! If you feel that it could be improved in any way - please comment, I'm open for suggestions. I'm also apologize in advance if there is some grammar mistakes, typos or wrong words and will be grateful for your corrections.
Thanks to the devs for the wonderful game!
Good bye and have fun!