Look at sequence of the flashing lights on the pinball machine.
Now check the paper in the side of the change/"medal" machine... right the corresponding numbers down in order of the flashing lights on the pinball machine... this is the code

Do you meant the "Z" thing from the model car? You hav to use it with the letter "Z" on the grid in the room with the invader game.
When u are in the invader game room, spin round the room tlll u get a view of a complete grid-looking wall. (it's blank, with nothing)

Then you click on the dot which the yellow monster is at in the invader game screen; which is the..:
(i will jus show the down left hand corner, right from the corner)

. . * . . .
. . . . . .
. . . . . .

click on the dot wher marked with an astric on my "drawing"...
Hope you solve it =)

goes into the "stud" on the wall in the invader room marked with a "Z"... you need to check the Invader game screen to see which alien is yellow, and then click on the corresponding "stud" on the blank wall

use your coin
HINT: (click box to highlight/fade)

Turn on light.
Click left leg of right bench to get a closeup of the two benches. Get FLASHLIGHT (under right bench). Move cursor to bottom so arrow appears and click.
Click on right side of air hockey table for closeup of right side. Click on hole then click to get PINBALL. Click bottom to exit (twice).
Go right. Click grey “bullet” to reveal punching bag. Click punching bag until it tips over (about 14 times). Click punching bag for closeup, then click close to the bottom to see underneath. Retrieve COIN. Exit closeup.
Click on ROSE VASE to retrieve. Select rose vase, click on magnifying glass to examine, then click roses to remove them. Click top of vase, then black circle to notice an object that you can’t yet get.
In front of you there’s a wall that curves. At the top of the curve, there’s a light grey box. Click where brown meets white on the edge of the curved wall for a view of the exit door that you can’t otherwise see. Click on the exit sign to notice the key, then click door handle about five times until the key disappears. Click bottom of screen and retrieve BACK ROOM KEY. Exit closeup (to punching bag scene).
Select coin (will be highlighted by a yellow square). Click small grey circle on top left of orange change machine. Click the buttons along the top of change machine, then click on the long grey bar for closeup of dispensing area. Get BLUE, WHITE and YELLOW COINS (aka “medals”). Exit closeup.
Go right. Select blue coin and insert into pinball machine. Select pinball and click on black dispensing area to drop it in the machine. Click on the pinball machine. Note the order in which the lights flash (red, blue, yellow and pink/purple). Retrieve the BLUE CAPSULE that fell on the floor. Examine the capsule and click on it to open and reveal a Kleenex box. Click on box to get a TISSUE.
Go right. Select yellow coin and insert into UFO catcher machine. Click the arrows on the front of the machine from left to right (up, right, down) and a white seal (aka “rag doll”) will drop to the floor. Retrieve WHITE SEAL. Click on thin blue line between 2nd and 3rd arrow buttons to retrieve SCISSORS.
Go right. Select vase and then click on ashtray to dump water. Examine vase, remove roses and click on top of vase to view gold coin (aka “medal”). Retrieve GOLD COIN.
Go right twice. Examine gold coin to see that it’s wet, then select tissue to dry it. Select gold coin again and insert into whack-a-frog machine. Click red button on left to start game and whack away. Don’t worry too much about your score. Retrieve GREEN CAPSULE. Examine green capsule to get FROG. Leave this screen, then come back to see a green rectangle under whack-a-frog. Click it to retrieve SCREWDRIVER.
Go left. Click on left side of orange change machine. Select screwdriver and click each screw. Click to remove plate, click again to get LIGHTBULB and click a third time to read note. Note which color lightbulb goes with which numbered coin (so yellow = 10, red = 5, blue = 3, and pink/purple = 4). Exit closeup.
Examine white seal and click on it to turn it over. Select scissors and cut belly to reveal and collect BATTERIES. Select flashlight. Click on top of flashlight to open and then select lightbulb and click top part to insert. Click middle part to open, and select each battery and click on the bottom part to insert. Click again to close and finally click the switch to turn it on.
Select back room key and click on door. Select flashlight and click on room to see. Click on machine, then select tissue to clean. Note that the yellow invader is three rows from the bottom and three columns from the left. Exit closeup.
Go left to face blank wall. Notice the grid. Click the dot that corresponds to the position of the yellow invader. You should see a Z in the wall. Exit closeup.
Go left. Click on right side of stairs leading to door (along right edge of bottom step). Click to retrieve HOOK (aka “stick”). Exit closeup.
Go left. Select hook and click on high cabinet. Click again to open it. Click the bottom of the middle switch to turn it on. Exit closeup.
Click right and then click door to exit back room.
Click left. Click on air hockey paddle on right side a couple of times. (Don’t miss the amusing translation, then shudder to think what *your* Japanese would be like.) Retrieve KEY PART. Click right paddle a couple more times until you score. Retrieve RED CAPSULE and examine to reveal PINK CADILLAC. Click pink Cadillac to flip it over, then select coin to remove the screw. Click what’s revealed to retrieve a PURPLE Z.

Now you have to choose which ending you want.
CONVENTIONAL ENDING (out the door):
Go left. Examine green frog, then select key part and click on the little black slot on the bottom of the frog to combine. This is the BOX KEY. Select box key and click on box beside door. Click to insert key and click handle to open box. Use the order of the colors on the pinball machine and the numbers that correspond to each color on the note in the change machine to get 53104 and enter it. Click the red button. Exit closeup.
Click on doors to open. Click on stairs. You’re out!

NOTE, ONCE YOU PERFORM THESE STEPS, YOU MAY NOT BE ABLE TO USE THE “SECRET” EXIT, EVEN IF YOU DON’T ACTUALLY LEAVE THROUGH THE CONVENTIONAL DOOR.

“SECRET” EXIT:
From the air hockey machine, go right. Click on the door to the back room. Go left to blank wall and click the dot that you selected before (3 up from bottom and three in from left). Select the Z and click to insert it. Click on the red chair, then go right to see light spilling from a doorway. Click the doorway. You’re out!