I think the mouse-based gameplay of Ultima Underworld could work surprisingly well on mobile or tablet, given that it has a much slower pace than 3D shooters.

I think the mouse-based gameplay of Ultima Underworld could work surprisingly well on mobile or tablet, given that it has a much slower pace than 3D shooters. OTOH, the thumb would obscure part of the screen. One could fix that by using a scheme similar to how the DS port of Mario 64 worked: wherever you tap-and-hold is the center of a simulated analog joystick, and the strength of the movement depends on how far away you move from the center of this point. The rest of the UI would also need some modifications obviously (given the lack of a right click mouse button). Still, I wonder if a slightly updated port would be successful.