You can either play the game and think upside down at the same time or you can simply sit in an invert table and thus begin the adventure. Whichever way you choose the rules stay the same.
Create full horizontal lines, reach the goal in each level, which is indicated at the right sidebar and clear levels. In upper levels not only that you will get bigger goals, levels will also be harder to complete.
However, you will always have fun with Upside Down Tetris!