As they build their melds and monitor the moves of their opponents, players alternately draw from the stockpile or discard pile. Canasta's focus on cooperation when played in pairs and its complex scoring system, wgame of slotshich incentivizes players for different game accomplishments, are what make it so captivating. In addition to planning how to construct their own melds, players also need to think about how to best assist their partners while impeding the advancement of their rivals. Another level of complexity is introduced by the use of wild cards, which are allowed in melds but have restrictions on how many can be used in a single meld.