Crash Twinsanity differs greatly in gameplay from its predecessor
Crash Bandicoot: The Wrath of Cortex. The

game is now played in a free-roaming
style rather than the follow-the-path gameplay of the past. Much like the Jak and Daxter series, Crash is accompanied by his nemesis Doctor Neo Cortex.
Crash can use Cortex as a hammer, perform
a spin attack while holding on to him, and can even use him as a snowboard in certain sections of the game known as 'Humiliskate'. In two places of the game, a path must be cleared for Cortex (to an a cappella rendition of Flight of the Bumblebee) as to avoid getting himself killed while running away from a swarm of bees and Evil Crash, respectively. These sections go by the name of 'Doc Amok'.
In the earlier levels, Crash and Cortex will fight each other (obscured by a cartoony dust cloud and stars), allowing the player to steer both of them throughout a part of a level in a section known as 'Rollerbrawl'. If the characters remain stationary for a while, the characters can actually be seen using a number of tortures on each other (including Cortex 'spanking' Crash and Crash banging Cortex against the floor respectivly). In some areas, only Cortex will be controlled, armed with a ray gun with a limited amount of ammo. If Cortex is without ammo, he will be defenseless and will scream and panic whenever he is moved.
Links
Official Website