1) Get a pc-mode-image or something comparable
2) Flash it to an USB drive (1 used a 128GB one from Samsung)
3) Put the USB drive into one of the USB ports of the VCS 800
4) Power on the VCS 800
5) Select "Debian GNU/Linux ... " from the boot options
6) Download Problemlöser from itch.io, choose the Linux version.
7) Chmod the binary to be executable (chmod u+x [FILENAME])
8) After the start, the game could be very slow, I pressed CTRL + ALT + DOWN and the CTRL + ALT + UP to switch the virtual desktop once and then return to the original virtual desktop, then the game runs in normal speed
9) Have fun. Play with the Atari VCS Game pad. Connect it via USB