Here's my first generated gameduino-200a.bit with the modified Makefile and source code. (most kept intact)
Disclaimer, though - this bitstream has been untested, and I will not take responsibility for any damage that occurs to any Gameduino until I make an update regarding this bitstream.
UPDATE: It works! I have finally tested the bitstream with xc3sprog and a CJMCU-FT232H FTDI-based JTAG/UART/SPI programmer from Aliexpress (https://github.com/m3y54m/cjmcu-ft232hq-programmer). But nonetheless, I will not take responsibility for any damage that occurs to any Gameduino. My Gameduino appears to be working with the new bitstream (tested audio, not video yet, should be fine though) and all programs should work!
Anyway, enjoy!