Well done! I'm terrible at shooters games, like this. So, typically I don't spend much time playing them. But I really like what you've done here. Next to Salamander, I think Relentless 64 will become my next favorite shooter game. Thanks for including the different difficulty levels.
I liked the PETSCII graphics on the intro screen, too, and how you carried that theme over into the game-play. Very cleaver.