One of the earliest games to ever feature on a "personal computer", co-written by Bill Gates, was Donkey — a driving game in which you had to avoid donkeys. For years, it's been missing from your life, but don't worry: now you can get it on iOS.
Sometimes referred to as DONKEY.BAS — that was it's file name — it really shows off everything that is great and good about 8-bit games. It is ridiculously simple: you only use on button, to change lanes. It costs $US0.99 in the app store, and it is worth every cent. [iTunes App Store]