How I did it.

Ingredient:

1 Raspberry Pi

1 Monitor

(in my case a old 21ยดยด TFT 4:3 with DVI Input) which made it easier to connect it to the Pi

1 Old Wardrobe (or a lot of ply wood)

I removed the silver coverage from the wardobe cutted out the arcade case and glued the silver coverage on again.

1 PC Speakers

1 ATMEGA 32U2 Board (e.g. NooGroove: see ebay)

1 Arcade Joystick from ebay

1 xArcade Trackball

A few Arcade Buttons 

1 green LED Stripe (for illumination)

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I used two existing Projects:

First Kade loader 

http://kadevice.com/loader-software/

with this one you can progamm your ATMEGA32U2 to emulate a Keyboard when a Button was hit.

Second http://pimame.org/

This is a great Project from Shea Silverman

It's a multi arcade machine emulator (and much more)