I recently got interested in these tiny arcade machines that you were able to find at pretty much any local retail store. At Walmart I got a Space Invaders one for $10 on clearance and made modified it to play all 4 games pre-programmed on the board instead of the 1 it shipped with which is a common hack that people have done. Then about a month later I bought another one from the same Walmart for $5 on clearance (how could you pass that up?!) and decided to try something different. This time I made the 4-game hack using the 4-direction joystick (hold the joystick in a direction and turn on the system to select a game), replaced the 3 AAA batteries with a rechargeable DS Lite Battery, and designed/3D printed a case for it in the style of a Gameboy (kind of). For some reason using the 3.7v DS battery worked perfectly fine. Originally I planned on making new buttons and changing the layout of them but then I decided it would be much easier to keep the original button PCB. The whole process went great without too much hassle.

Here are some pictures!



Full size image links:
https://ibb.co/9th5whx
https://ibb.co/q1JxzL7
https://ibb.co/K6qf5Yq
https://ibb.co/yn4y1Xz
https://ibb.co/FJW9C2p
https://ibb.co/vDdBTXn

Can you show us how you hacked it?

Sadly I don't have any pictures of the process other than the ones above, but basically the thing comes with a screen, a control board, and the main PCB. I first started with the 4-game hack. The joystick on the control board is a 4-directional stick. On the main PCB, 4 connections can be bridged with ground to select the game. So I took each direction from the joystick and wired them to the bridging points. This makes it so if you hold the joystick in one of the four directions, one of the four games gets selected. If the joystick is in its original state, a debug program is run.

Next, I wanted to make it work with a rechargable battery instead of AAAs. The only rechargable battery I had laying around was an old DS Lite battery; plus they're relatively cheap so it didn't hurt to use one of those. The input volatages of the DS battery and the AAAs aren't the same, but it worked so . I wanted to make it as slim as possible to fit in the case so I removed the battery's plastic casing and sticker and hardwired it to a battery charger board I had laying around from a previous project with a switch to enable and disable power.

I then layered each part on top of each other: speaker on the bottom emitting sound out the back, battery next, controller board next to the battery, the charging board glued on top of the battery, the main PCB, and the LCD.

Finally, I designed a case in Fusion 360 after taking a bunch of measurements and 3D printed it in colors that matched the existing color scheme of the buttons and screen: red and black (luckily it was those colors because those were the only 2 colors I had). I printed the case using a snap-shut mechanism so I could easily access the inside if I needed to. The first print was successful, so I put everything together and got it working. After that I designed a front "plate" in Illlustrator and printed it on paper and glued it to the front of the system. Since it was paper, there were obvious cutout marks made by the Xacto knife I used, so I simply colored the white with a black sharpie and it looked amazing to me.

So yeah, that's a more thorough summary of how I did it.

Looks cool as, very small - you did a great job fitting it all in such a tiny case.

Looks like you'll have to add some more games to it! https://www.youtube.com/watch?v=A0I3cqWFubc