I have left a comment on yoyogames; This is indeed really good, with two exceptions: 1) Game does not save the progress (?) 2) Finding all flowers does not grant any reward, as unlockable or level editor or anything else of this kind.
1) yes it does? have you downloaded the game properly? the game produces and reads an INI file automatically, so if you restart the game go back to menu and press start again you can select the level you want. 2) Nope, but in the start menu it shows an achievement. Finding the flowers just provides extra gameplay.