In Odin you want to empty your hand as quickly as possible by sending all your Vikings into the world.
The game lasts several 'hands', with each hand consisting of one or more rounds. The deck contains cards in six suits, each numbered 1-9, and each player starts with a hand of nine cards.
The leading player places a single card on the table. The next player passes (but can play on a future turn) or plays the same number of cards (or one more than that number) of a higher value. When you play two or more cards, the cards must have the same number or color, and the value of these cards is created by placing their numbers from highest to lowest. For example, if you play a blue 3 and blue 6, their value is 63, not 36. When you play and are not in the lead, you must take one of the cards from the previous turn into your hand and discard the rest.
Play continues around the table until either one player runs out of cards, which immediately ends the round, or all players pass in succession. In the latter case, discard the last played cards; the person who played these cards lays down a single card to start a new round. Alternatively, if the leading player holds cards of one color or number, they play all of these cards at once to end the hand. When a hand ends, each player scores 1 point for each card they still hold.
If no player has at least 15 points, shuffle the deck and start a new hand. If someone has 15 or more points, the person with the fewest points wins.