I don''t think it''s the gameplay focus of simple games - they can have excellent graphics/sounds as well. Consider for example racing games like Colin McRae Rally: There is not much to know about playing it, accelerate, brake and steer... but we played this game like madmen! And the graphics were really good, the physics is still unequalled. What''s the gameplay here? Actually it is just being better/faster than the previous best time (or your friends).

Like someone already stated: a good game is easy to learn but difficult to master. Why easy games are so appealing? I guess easy access is a big factor as well as the possibility to play it whenever you have a short sparetime. Other than that we''d need a psychologist to explain why beating a highscore or time is so rewarding for many of us...

Btw, a pause function is a must in any realtime game - not having one is a quick way of alienating customers...

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