I remember playing each Tex Murphy game for whole afternoons/evenings up to 4am on a few occasions before my whole body complained and made me sleep. Stupid body.
They just captured my attention so much I couldn't stop playing, same for Deus Ex (that's part adventure right?
).
It took essay deadlines to stop me playing Overseer so much. No other games have captured my attention so much before or since. Loved them.