Modern retrocomputing made the way I like:

MEGA65: the  8-bit computer: an open-source new and open C65-like computer.

The 21st century realization of the C65 heritage: A complete 8-bit computer running around 50x faster than a C64 while being highly compatible. C65 design, mechanical keyboard, HD output, SD card support, Ethernet, extended memory and other features increase the fun without spoiling the 8-bit feel. Hardware designs and software are open-source (LGPL).

Here their code repositories