That would be Gargoyle Revenge. The concept isn't original, but that's nothing new. The gargoyles definitely look a lot like the picture you posted from Heretic, but it's not a direct rip. The gaming industry is known for games ripping each other off (or spoofing each other), and most of the time it's legal. Same with television. I don't watch Family Guy that often, but in the episodes I've seen, they've had Optimus Prime, Soundwave, Kool-Aid Man, the Thunder Cats... well, it goes on and on. Then there are those awful movies like Meet the Spartans that are nothing but references to other movies. I don't condone piracy at all, but it seems like copyright law allows you to steal almost any concept, storyline or likeness, as long as there's something original about it. I've played lots of games and said to myself, "This is just a shameless rip off of Space Invaders/Pac-man/Super Mario Bros./etc., and I won't reward the author by putting their game on my website." I don't feel that way when I play this game. I'm not an expert, but it all looks legal to me. It's at least somewhat original, and it's fun, and I like it.
Incidentally, I'm amazed that courts found that K.C. Munchkin infringed Pac-man. There have been thousands of games over the years that have exactly duplicated famous games (goodbye Scrabulous), or blatantly stolen graphics, or used the very source code of a copyrighted game to create a bootleg game with new graphics to pass it off as an original game, this case is the only one I'm aware of where an original game was deemed to violate the copyright of another original game for using a similar concept. While the concept is indeed similar -- a guy moves around in a maze eating dots and avoiding bad guys, unless he eats a power pill that lets him eat the bad guys -- if you actually play the game, they're totally different. Besides the different graphics and different mazes (some had invisible walls!), the dots move around the maze! The fewer are left, the faster they move, and soon you're chasing the dots at the same time as avoiding the "ghosts". Sadly, video games were new at the time, and the courts were largely ignorant of the video game industry. No court would rule against K.C. Munchkin today. Yes, it has a similar concept to Pac-man, but every game has a similar concept to some other game. If every game had to be completely original... well, they probably would have stopped making games in 1982.
Today entirely the maniac there is no excuse with the article.