Out There: Do the best games never end?

US game academic Eric Zimmerman was recently asked by the Jace Hall show to contribute his thoughts about its 50 favourite game endings list. But rather than coo over Portal 2 or something, the eggheaded killjoy instead took the opportunity to state that his favourite games don't have endings.
...traditionally games don’t have endings. Games like Basketball, Chess, and Scrabble are activities meant to be repeated, rather than a series of levels to be beaten or a story to be played through. Many digital games, from Asteroids and Tetris to Street Fighter and Smash Bros to Sim City and Civilization are on this model of games designed for repeated play – and they don’t have endings. I prefer these kinds of games, as they are less premised on a desire to imitate cinema or linear storytelling and they are more focused on games as games as systems of rules that reward deep and repeated exploration.
Obviously, each of the games Zimmerman likes do indeed have endings - many endings. A game of Street Fighter ends with a victory or defeat screen, and beating the arcade mode on hardest difficulty grants you the above reward. Even the longform narrative-based games that Zimmerman is really talking about often have replayable elements, whether because of an unlocked hard mode, hunts for collectibles and secrets, score attack sub-modes or co-op sections.
But, yes, properly replayable games depend on rulesets over their stories. Playing the same story over and over would invite boredom, but a beautiful set of rules will never grow old.

http://www.edge-online.com/news/out-...ames-never-end

Highly addicting to the game will makes you want to play it again and again. Even when it gets really easy its still fun to play and see how high you can rack your health up and to see how much harder the game will get.