Thanks for playing, I really appreciate it. Apart from the things I knew by programming the game, I figured out major parts of the strategy by playing myself, so I think this is pretty normal. If you were going to give it a shot again some time, I’ll leave you the following tips: The larger your combo is, the more time & score you’ll get. So taking your time to find larger combos is usually more effective in order to stay alive and score higher than simply just rushing it. Also, always try to get as many sheep/chicken into the combo as soon as possible, i.e. try to leave as few on the board as possible, this will greatly increase your chances to score an all-clear which is essential in order to get high scores. Try to not delete more than one piece per hand (as it gets progressively more expensive within a hand) and only delete if placing it would make the board-structure worse.
Regarding your question: Piece shapes are generated by a bag system which guarantees the equal distribution of all possible shapes even in shorter periods of time. In this particular case, you’ll see every shape twice before you see an arbitrary piece for the third time. colors within the piece are random, and yes, some patterns will be much harder than others, but this is the point where the player’s positioning skill can shine :)