Gemini Rue
(which looks like it's from 1990 but actually was released only two weeks ago; very good indie p&c adventure game with a strong Blade Runner and Beneath a Steal Sky vibe; I'm currently playing and enjoying it)
Beneath a Steel Sky is a good recommendation on its own imo, mainly because it's still a good game and freeware now.
Or one of those many other great games available on GOG, e.g.
- Barozi's recommendation (which takes your life and then some) or its successor which was released on GOG today
- one of my all-time most favourite games (I like it far more than Caesar III, which seems to be more popular though)
- a game from the Age of Wonders franchise (GOG got 3 of them)
- which is the spiritual successor to another one of my all-time most favourites
- or how about this legendary TBS franchise or this one
Or any of the 4 free ADG King's Quest/Quest For Glory remakes, which will drive you mad (don't believe the "soon!" button on KQ III Redux, in fact it's already been released recently).
As I've never played a game with a touchpad only, I don't know if a p&c adventure game would actually work, so like others I'd primarily recommend turn-based strategy or a city building/economic sim.
In case you're not interested in any of those, then here's a special tip which should definitely work with a touchpad and probably ruined more lives than Civ and HoMM together: Peggle.
