Here is a list of my favorite adventure games for PC and iPad.
PC
King’s Quest (1,2,3,4 – the text ones)
Gabriel Knight (1, 2, 3)
Dark Seed
Ripper
Dark Fall
Lights Out
The Dig
Loom
Black Dahlia
Safecracker
Alone in The Dark 1
iPad
The Room (1, 2, 3)
Myst
Riven
Forever Lost (1, 2, 3)
Machinarium
Device 6
Facility 47
Oceanhorn
Another World
Limbo