Kung Fu Flash is a Commodore 64 cartridge by Kim Jørgensen that is able to emulate other cartridges, such as Epyx Fastload, Super Snapshot v5, as well as load PRG files and use D64 disk images.

This enables you to play most of your favourite C64 games directly from this cartridge.

As Kim describes it: "Just place your desired CRT, PRG or D64 files on a FAT formatted microSD card and use the built-in launcher to execute them."

Kim Jørgensen's Github page with Kung Fu Flash software, descriptions, guides, BOM lists and everything else you need: github.com/KimJorgensen/KungFuFlash

AutumnHippo sells the Kung Fu Flash in the following variants:

Ready-to-use: Completely finished Kung Fu Flash, ready to accept your MicroSD card and stick in your C64. Mounted with 6x6x12 mm tactile switches for easy mounting into 3D printed case, as well as the USB port mounted. Flashed with the Kung Fu Flash firmware.
Kit: The PCB with most components already mounted, as well as the rest of the components loose. You will need to mount these components yourself: MicroSD-card socket, MicroUSB socket (optional), and 3 tactile push buttons, as well as program the chip. Surface-mount soldering (SMT) required.
PCB only: Just the bare circuit board with no components. Source your own components via Kim Jørgensen's BOM list, solder everything yourself, and program the chip.

Please note, the PCB only and kit variants will require a certain soldering skill level. Involves soldering pretty small surface-mount components, which is probably not a good beginner's project, but should not be a problem for a slightly experienced solderer with a hot air rework station or similar.

We also offer a fitting MicroSD card if you need one for your Kung Fu Flash. Even a couple of GB is plenty large to store all your C64 games.

The Kung Fu Flash reviewed by Adrian's Digital Basement.