Mad Hatter in American McGee's Alice
In American McGee's Alice, the Mad Hatter is more sadistic than he was since Alice was in Wonderland last time. He is no longer obsessed with tea parties, and instead captures, imprisons, and modifies the inhabitants of Wonderland into his automatons. At precisely six o'clock every day, he comes to check up on his cruel experiments (and deny them their tea). The brutality his subjects have to go through is shown when Alice sees the Dormouse and the March Hare. The Mad Hatter only started turning the two into Automatons, horrifically mutilating their bodies, and the two are still alive and aware of the process. What purpose the Mad Hatter has for turning them into Automatons is unknown.
The Mad Hatter represents the truth in Alice's mind, reminding Alice that she is denying the truth. When Alice says that she fears nothing, but the Mad Hatter replies by telling her that she fears much, like a return trip to Rutledge Asylum, and the memories that drove Alice there in the first place. He also seems to know how Alice could have avoided all that, leaving gamers to wonder if he actually knew how Alice could regain her sanity, or perhaps forshadowing Alice's guilt, which is talked about by the Jabberwock.
The Mad Hatter himself seems to be an Automaton as well, because when he dies, his head is blown off his head, and sparks are coming out of the base of his neck. The fact is also that his attacks involve shooting out projectiles from his hands and even his hat, meaning that he found a way to turn himself to part Automaton, part flesh himself. However, the truth how he did it to himself is unknown, since Wonderland is all in Alice's mind, so nothing really makes sense.
His attacks include shooting finger missiles, launching explosives out of the top of his hat, and also cause Alice to go into 'drug mode', where the screen goes into a sort of drunk-like view, the screen is tinted green, and the silhouette of the Cheshire Cat can be seen. After every two bell rings, the Mad Hatter leaves and a couple of his Automatons have to be fought, which can be useful since each one leaves behind a large Meta Essence. When the bells ring again, the Mad Hatter reappears and does the same things as before.
The Mad Hatter is responsible for the death of the White Rabbit in 'Herbacious Border', almost immediately when the level starts, by crushing the then-small Rabbit underfoot. He also captures Alice in the Red Chess pieces realm by knocking her out, a small while after Alice successfully brought a White Pawn over there to change into a White Queen.
Alice: Madness Returns
The Mad Hatter makes his appearance in Alice: Madness Returns in the second major level in the game, Hatter's Domain. Hatter's labyrinth of a factory, once dedicated to constructing and maintaining trains for the Looking Glass Line has been overtaken by the Dormouse and March Hare. The two power crazy mammals have dismembered the Hatter and are using his body parts to operate the factory.
When Alice meets the Hatter he is nothing but a head yelling at her from the ground. She quickly finds his body and mechanical arms reunite the head and torso together. When Alice asks the Hatter for information about what is destroying Wonderland he tells her that once she finds his arms and legs he will help her. Alice finds Hatter's arms are under control of the Dormouse who is using them to melt iron. The legs are under control of the Hare who is using them to power a wheel along with a legion of Dodo's.
Upon being reconstructed, Hatter and Alice make their way through the factory to where the trains are constructed and see a massive citadel-like train making its way out of the factory. The Hare and Dormouse make a feeble attempt to kill Alice, but the Hatter destroys their giant robot. The force of the leviathan train leaving the factory causes the factory to fall apart and the Hatter, Dormouse and Hare seen participating in one last tea party before the factory collapses on them.
The Hatter also shows up in Radula Room combat challenges as a huge figure looming over the battle area.