Each player starts with slices numbered 1-16. On a turn, you roll 3-5 dice (depending on your current top slice) and the chance die. After your roll, if any single die or the sum of any number of dice matches your top slice, you remove it; keep removing slices as long as the numbers add up. If, for example, you rolled 1, 2, 5 at the start of the game, you could remove the 1, 2 & 3 slices.
You now either end your turn or roll again. If you roll again and fail to remove a slice, you must place slice cards back on your deck as a penalty.
The chance die may give you the opportunity to swap decks with another player — or force you to swap with whoever has the largest deck! Alternatively, you might gain the Nope! token and use it to block a deck, whether to keep an opponent from removing cards from it or to protect your deck from being stolen.
Countalope can also be played as a multi-round game, with players scoring 1 point per card removed, with a game ending when someone has 16 points. Whoever reaches 100 points first wins.