Free Apps I develop in Engineering,games,lotto ....

Hi, I have released a few free apps on Google Play (Lotto/Random numbers generator,Sudoku games,onLine radio/music streaming,Engineering/Chemmathsdroid and more ) that u may want to try/look at/comment on. In google play store search on my business name : ChemEng Software Design or chemmathsdroid

Also a question on "what makes u try a App?" is it the type of icon ?, the overall look and feel of the screen shots ? is it the cool factor ? or is it because someone suggested it to u ? or something else ?