Question: Who created the game which uses Palladium's Megaversal system and created in August 1990?

Context paragraphs:
Rifts (role-playing game): Rifts is a multi-genre role-playing game created by Kevin Siembieda in August 1990 and published continuously by Palladium Books since then.  "Rifts" takes place in a post-apocalyptic future, deriving elements from cyberpunk, science fiction, fantasy, horror, western, mythology and many other genres.

After the Bomb (game): After the Bomb is a role-playing game originally published by Palladium Books in January 1986.  It uses Palladium's Megaversal system and features mutant animals – anthropomorphic and otherwise – in a post-apocalyptic setting.

Valley of the Pharaohs: The Valley of the Pharaohs is a role-playing game written by Matthew Balent and published by Palladium Books in September 1983.  Released several years before Palladium established the Megaversal system, uniting all of its game lines under a single ruleset, the mechanics of "Valley of the Pharaohs" differ in many respects from the one currently used in Palladium role-playing games.  It has been out of print for more than 25 years.

Nightbane: Nightbane is a dark fantasy role-playing game and setting created by C. J. Carella and published in 1995 by Palladium Books.  The game uses Palladium's Megaversal system, which is also used by the multi-genre game "Rifts" and the horror game "Beyond the Supernatural", among others.

Turtles Go Hollywood: Turtles Go Hollywood is a supplement for the "Teenage Mutant Ninja Turtles & Other Strangeness" role-playing game.  It was published by Palladium Books in 1990 and uses the Palladium Megaversal system.

Rifts Chaos Earth: Rifts Chaos Earth is a post-apocalyptic role-playing game from Palladium Books.  It is a spinoff and prequel to their popular game "Rifts", which uses a similar form of Palladium's Megaversal system.

Mutants in Avalon: Mutants in Avalon is the fifth supplement for the "After the Bomb" role-playing game, originally based on and compatible with "Teenage Mutant Ninja Turtles & Other Strangeness".  It was published by Palladium Books in January 1991 and uses the Palladium Megaversal system.

Mutants Down Under: Mutants Down Under is the third supplement to the "After the Bomb" setting of the "Teenage Mutant Ninja Turtles & Other Strangeness" role-playing game.  It was published by Palladium Books in June 1988 and uses the Palladium Megaversal system.

Heroes Unlimited: Heroes Unlimited is a superhero role-playing game written by Kevin Siembieda and first published by Palladium Books in 1984.  The game is based upon the Palladium Books Megaversal system and is compatible with other games that use the Palladium system.

Mutants of the Yucatan: Mutants of the Yucatan is the fourth supplement for the "After the Bomb" role-playing game, originally based on and compatible with "Teenage Mutant Ninja Turtles & Other Strangeness".  It was published by Palladium Books in July 1990 and uses the Palladium Megaversal system.

Supporting paragraphs: Nightbane Rifts (role-playing game)
Answer: Kevin Siembieda