In a nutshell, Eureka is a stricter and more challenging game than Spades. The object is to get the exact number of tricks that you bid. It can be a real challenge. You start play with one card per player, bid on whether or not you can take the trick, and then play the hand. If you succeed in making your bid you get 10 points plus the one successful bid [totaling 11 points] . If you don't you only earn 1 point for each trick you get. In that first hand you either bid 1 or 0. If you bid 0 and get none, you get 10 points. If you bid 1 and get it, again you get 11 points. If you bid 0 and get 1 you only get 1 point. The next hand each player gets 2 cards and go through the same process.

With 4 players, this goes on until, in the last hand, everybody gets 12 cards each. With 3 players it continues until everybody gets 17 cards.

The difficulty is in trying to figure your odds in winning tricks when there's no way of knowing what the highest card in any suit is dealt. With 1 card, it's possible that nobody has a trump card and the person who leads might win just because they have the highest card in that suit. You also have the edge early on if you are the player leading. If trump were, say, and you lead with the 3 of and nobody else has a or a you could win the trick with that lowly 3 of

It gets really tricky in mid-game because there's, again, no way of knowing how strong your higher card is in relation to what others have been dealt.