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 1, there is 4 light keys, and a slow speed game. If you are starting with the Simon game, this game is ideal for you!
The Simon Game level 1 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.