MASTERCHESS was a budget game sold by the British software company Mastertronics. It is very weak and possibly the weakest commercial chess game ever made for a Commodore 64.
Press the ESC key on your PC for the Options Menu.
You can read about the original MASTERCHESS here:
The playing strength of MASTERCHESS is approximately 900-950 ELO (1100 - 1150 USCF).