Try to memorize the serie of illuminated keys and reproduce it, at each step a new key is added to the serie and the game becomes more difficult. In the level 2, there is 4 light keys, but speed game is faster. If you find Simon game level 1 too easy, this game is ideal for you, because a little more difficult.
The Simon Game level 2 on this website is totally free, it's a good memory trainning, you play as many times as you like. The serie is randomly generated so the game is unlimited.