Gaining Perspective does this very well, where there is still unique actual gameplay that happens once you hit immobility. In my mind, for a game to not have immobility be the end, you essentially have to have one of two different options:
- A game design that allows you to still do most things while immobile. A number of people in this thread have already described options, but essentially think of something like a monarch where you can still reign over a kingdom even without actually moving.
- Specifically designed gameplay around immobility. Gaining Perspective does this, where you actually have this be its own section of the game with very specific and unique things happening.