I remember playing this game when I was younger, on the original iMac, I probably played it somewhere between 1998 - 2002? It was a shooter game, and the main character was dressed in all black, and looked like their head was fairly triangular. You could jump off things and glide at times, and had a little gun on your right hand. There was a weird little decoy thing you could deploy at times as well. I can't for the life of me remember the name, but I wouldn't mind checking it out again! Please let me know.