The 500 Card Game is the greatest card game ever devised (arguably). It is most popular in Australia, New Zealand, parts of America, and Canada. Download the software that allows you to play against the computer here. Being so wide spread, there are very many local house rules. The current version includes options to play with most of these. It also supports most non-standard screen resolutions.

People who do not enjoy 500 will certainly enjoy the BRIDGE card game or EUCHRE or CANASTA or WHIST or one of the eleven games contained within the RUMMY family of games.   More detail...