Angel Inokon has a good blogpost about the affordances of Katamary Damacy (the PS2 game in which you have to roll a ball to collect items located everywhere):

Three Design Principles Katamari Damacy gets right: - Affordances – affordances enable designers to create gameplay that leverages the natural limitations and features of an object. One of the clear affordances of a ball is that it rolls. Everyone, regardless of age, recognizes a ball and can easily conceive it’s primary function. (...) Users can quickly get immersed because the rolling action is consistent with the simple affordances of a ball. - Visibility – gamers need awareness of the mechanics of gameplay through visuals and audio feedback. Two feedback mechanisms built in the game include a progress icon and sounds. The player is given a simple icon on the corner of her screen that shows the size of the katamari. (...) Gamers need lots of information. Integrating visibility principles allows designers to keep pumping the right information when they need it. - Constraints – constraints prevent gamers from making errors that could decrease enjoyment of the game. Katamari Damacy centers around a single rule – players can’t roll up something that is bigger than their ball. If the player got lost in an area with many big objects, she could get frustrated. So the game blocks the paths to larger objects until her Katamari is large enough to roll over the barrier. It makes the game easier to explore and less overwhelming by essentially modularizing the levels (174). Failure is a critical aspect of gameplay, however good designers know how to constrain the environment so players stay immersed in the game.

Why do I blog this? because I like Katamari and agree with that principles which connects human-computer interaction a la Don Norman to an efficient video game design.