So I have followed through on my recent goal of creating a variant for MACE. Since my knowledge of the entire MACE system is still that of a novice, I decided to take the smartest route and instead create a variant for MACE Lite, the lite version of MACE which I am much more familiar with. Aaron 'Relentless' White, the creator of MACE, has given this project his blessing, and is very welcome to adapt Mutant MACE Lite into a 'non-Lite' variant for MACE.
Mutant MACE Lite is an homage to the excellent RPG Palladium made for Teenage Mutant Ninja Turtles (based off the cool comics, not the mainstream TMNT nonsense). As a variant, it allows players of MACE Lite to create mutated animal fighters. You know the type... humanoid animal mutants trained in the martial arts and gifted with extraordinary animal powers.
I have the first incarnation of Mutant MACE Lite available for download here in pdf form. It may remain as is, but will most likely get altered somewhat as I get feedback from Aaron and other players of MACE. My concern is if the Animal Mutations properly balance out amongst each other, and that none of them are too strong or too weak.
Please check out Mutant MACE Lite and tell me what you think. I have also included for download a pdf file of the original MACE Lite by Aaron White, as my variant cannot be played or playtested without it.
Enjoy!
Peace, Errin : )

The Mutant MACE Lite rules in non-pdf form
THE RULES FOR MUTANT MACE LITE:
Mutant MACE Lite is an optional variant to be used with the Martial Arts Card Engine Lite Edition. Mutant MACE Lite cannot be played by itself and can only be played as optional rules to MACE Lite. The rules in this MACE Lite variant are used to represent mutated animal fighters in the world of MACE.
If Mutant MACE Lite is to be used with MACE Lite, at the start of the game, before each player has drawn their 5 card hand, the full deck is shuffled and each player draws one card to determine the Animal Mutation for their animal mutant fighter. The face value of the card drawn determines a specific Animal Mutation, with each Animal Mutation having a special rule that alters gameplay for the mutant animal fighter. After an Animal Mutation is determined, the player determines what type of animal their mutant fighter is, as well as how their Animal Mutation works for their fighter. Cards drawn to determine mutations are then returned to the deck, the full deck is re-shuffled, and the players draw their 5 card hands to start the game of MACE Lite as usual.
Use the following chart for which card value determines which Animal Mutation: Joker = Feral Fury, Ace = Heightened Metabolism, King = Physical Superiority, Queen = Regeneration, Jack = Invigoration, Ten = Lightning Reflexes, Nine = Bestial Strength, Eight = Animal Magnetism, Seven = Acrobatic Agility, Six = Natural Armor, Five = Increased Movement, Four = Great Size, Three = Stretching Limbs, Two = Poisonous Venom.
The following rules are for each Animal Mutation, and their use overrules the regular use of certain rules from MACE Lite when Mutant MACE Lite is used as a variant:
Feral Fury = If you play a Joker card, you may choose to have it count as twice the value of the top card in the discard pile instead of being equal to the value of the top card in the discard pile. However, if you play a Joker card at twice it's value for anything other than taking Damage, you do not draw a card to replace it.
Heightened Metabolism = At the start of the game when drawing your 5 card hand, you draw a 6 card hand instead of 5. However, the first time you play a card, you do not draw a card to replace it.
Physical Superiority = At the start of the game when drawing your 5 card hand, you draw a 7 card hand instead of 5, then discard 2 cards from your hand before the rest of the game begins.
Regeneration = When you discard two cards due to Damage, draw another card. If that card has a higher value than either of the cards you discarded, you may keep the drawn card in your hand, otherwise you must discard it.
Invigoration = Once per Combat, when your hand is down to one card, you may choose to draw a card which is then added to your hand. Once this is used during a Combat, it may not be used until the next Combat.
Lightning Reflexes = Whenever you play a card for Momentum or a Momentum Boost, increase the value of the card you play by +1. The additional +1 may not be counted to Move +1 space due to Momentum Boost.
Bestial Strength = Whenever you play a card to Strike, increase the value of the card you play by +1.
Animal Magnetism = Whenever you turn over a Charge card in order to use it to Blast, increase the value of the card you turn over by +1.
Acrobatic Agility = Whenever you play a card to Dodge, increase the value of the card you play by +1. The additional +1 may not be counted to Move +1 space due to Dodge.
Natural Armor = Whenever you play a card to Block, increase the value of the card you play by +1.
Increased Movement = Whenever you Move due to Momentum Boost or Dodge, you may choose to Move +1 space in addition to the number of spaces you Move.
Great Size = When you suffer Knock Back, the number of spaces of Knock Back is equal to a quarter (1/4) of the Damage taken instead of half (1/2) the Damage taken.
Stretching Limbs = Your fighter's Reach counts as two spaces rather than one when making a Strike, but another fighter counts your Reach as one when they are making a Strike or Move.
Poisonous Venom = Once per Combat, if another fighter discards a card from their hand due to Damage from your Strike, you may choose to play a card from your hand. If so, the fighter receives Damage equal to the value of the card you played, then you draw a card to put in your hand to replace the card you played. Once this is used during a Combat, it may not be used until the next Combat.
Optional Rule: Mutant animal fighters may have more than one Animal Mutation if all players involved agree. If so, players draw more than one card when determining their Animal Mutations at the start of the game, with the amount of cards drawn equal for all players involved. If the same Animal Mutation is drawn more than once by a player, it is not counted and another card is drawn in it's place to determine a different Animal Mutation instead.