I can't remember exactly. The main thing about Chu Chu Rocket is just at the time it had the most recent version of the Japanese Dream Passport browser you could get in English.

The American browser was useless garbage, but some games bundled the Japanese one on disc. The trick was, some of them were locked such that they'd only go to like, the game's website and hid other features and stuff. But Chu Chu was either unlocked by default or could be permanently unlocked so you could use it as a normal web browser.

I think I played the actual game like once, and sucked at it. I just wanted the DP

Oh, I'm sorry, I may have been over-assuming. I have been hacking together power cords since I was nine and sort of forget that it's not a universal experience

If you obtain any cable with that connector (which is formally called mini-din 4 pin) and cut it in half, then strip the wires inside, and then do the same with a power supply of the right voltage, you can simply twist the bare wires from each cable together and presto, you have a supply suitable for verifying if the thing even works

You do need to figure out which of the four wires correspond to the pins you need however, and ensure that the pinout is correct, because if you get it backwards you will very often fry the whole device, so you need to have a multimeter and know how to use it.

also, a cable assembled like this has several safety concerns, not in the sense of electrocuting yourself (that can't happen at low voltage) but in terms of putting too much power through wires not intended for it, or the bare conductors shorting together, both of which can cause a fire, but usually not unless you leave it running for quite a while.

For a 2 minute power on test to just see if the machine functions at all, this sort of arrangement is the cheapest and simplest. if it actually works, and you decide you want to put a little more effort into making the machine usable, then there are options for building a long-term solution - ideally, you would buy a bare connector and solder the internal contacts to the wires on the donor power supply.

I wasn't sure if you have any electronics experience so I didn't know if I'd be talking down to you by explaining all this, apologies if so. If none of it's stuff you've done before though, then it might not be an ideal first project.