The demo discs had contents that would only unlock after a certain date. This device was used instead of the Gamecube's internal clock so that the store owner's could't cheat by setting the console's clock foreward

The games were all just NTSC-J, meaning they would also be accepted by Japanese consoles.

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If your looking for the exact Issue, here it is

In total, there were 35 of them released in North america and 26 released in PAL. 7 of them beeing alternative versions for Australia. The final PAL version was released in April of 2006.

Cleaning the contacts can help too. At least it was enough for mine

You could try to carefully put some solder on the pins that connect the power board to the motherboard. Or just clean them

Here is a walkthrough for the shown Demo disc youtu.be/K01GVQj-mRQ?...

They also made commercials for Mario Strikers Charged Football on Wii. But sadly, they did not put any Stickers with him on the cover of that game.

I guess if you really need an arcade stick for Gamecube, this will do the job just fine but if you want something of better quality, Hori got you covered with their arcade stick for Gamecube

The Spongebob Squarepants movie + Tak 2 staff of dreams bundle has an alternative cover art for the french version featuring the french cover for Spongebob movie game