Phineas And Ferb In Gamesmash is an online game at 43g.Com. You can play Phineas And Ferb In Gamesmash in your browser for free.Another action-packed Phineas and Ferb Game! Play GameSmash and build your own roller-coaster! Start your roller-coaster building adventure by selecting your favorite Phineas and Ferb character to play the game! Choose from Perry, Isabella, Jenny, Doofenshmirtz and of course - Phineas and Ferb! The next step is to select a cart. There are more than 10 crazy options for a cart to choose from. The first 4 are available while the rest need to be unlocked and will become available as you progress through the game! The next step, and the most important one, is for you to build your roller-coaster track!