Two-player card game simulating a fight between kaiju (giant monsters). Based on a PC game of the same name, the goal of Colossal Kaiju Combat! is to amass less damage to your kaiju than your opponent. Play comprises three turns, each of which is comprised of three rounds. In each round players lay 3 attack cards from the common Combat Deck, from their initial hand of 5 attack cards, to be their fighting cards for that round. Cards are then revealed simultaneously, starting with each player's leftmost card. Once those are resolved, the second of each player's cards are revealed and resolved. And again for the last cards. At the end of each round all cards are returned to the players' hands and an additional card is drawn. At the end of the turn (3 rounds), all cards are discarded and another 5 cards are dealt to each player from the Combat Deck. Each player is given, or chooses, a kaiju card at the start of the game which determines stats in four categories as well as buffs such as claws, teeth, tail, etc. which are referenced on various action cards to alter their effects. The stats limit the types of attack cards that can be played as each action card consumes specified amounts of three of the four stats. The fourth stat determines how much life the kaiju regains at the end of each turn. Finally, each attack card is categorized as either a Quick Attack, a Combo Attack, or a Strong Attack and are resolved in that order, possibly rendering an opponent's attack inert. At the end of the game, the kaiju with the least total damage over the course of the game is declared the winner.