King of Tokyo: Origins is a standalone game in the King of Tokyo series that's meant to serve as an entry point for new players since it's a smaller, more affordable package. The game includes four new monsters, an assortment of new power cards mixed with older ones, energy cubes, and green dice with yellow characters.
Gameplay remains the same as in the original game: To win, be the first to score 20 points or be the only creature still standing.
On a turn, roll six dice, which show the following six symbols: 1, 2, or 3 points, energy, heal, and attack. Over three successive throws, choose whether to keep or discard each die in order to win points, gain energy, restore health, or attack other players. When you attack, if you're outside Tokyo, you hit whoever is in Tokyo; if you're in Tokyo, you hit everyone else! If someone's health drops to 0, they're out of the game. (You can't heal damage while in Tokyo, and the only way to leave town is to have someone attack you...which might put you at death's door.)
When you gain energy, you store it in cubes, which you can use to purchase power cards, which have a permanent or temporary effect.