If you are looking for a for Mapper 202 or need help with how to use an existing ROM collection, let me know so I can find the right documentation for you.

: These carts use specialized "mapper" chips to switch between different memory banks, allowing multiple games to share the limited hardware space of a standard cartridge. Common Game List Patterns

Often, the "300" games were actually 50 unique titles repeated with different names or starting levels.

They were glitchy, chaotic, and magical. The menu screens were often a mess of repeated titles, graphical errors, and questionable English. You might find Super Mario Bros. listed four times, or bizarre hacks where Mario shoots a rifle. Yet, for a kid with limited budget, it was a gateway to a massive world of gaming.

When the menu loads, you may notice graphical corruption (flickering text). This is authentic. The original cart had glitchy menus. To stabilize it, try toggling "Hardware rendering" or "Disable sprite limit" in your emulator settings.