Pokemon Black says I have 500+ hours on it. Seeing how I leave my DS in sleep mode plugged in over night instead of actually turning it off, and that black stays in the wireless mode while closed, the 500+ should be reduced to about 70.
One I actually wasted the most time on... Maybe Unreal tournament on my old Dreamcast. Played so much in my childhood.
If not the pokemon series would be it. In all the games would probably actually be 1000+
Red, Yellow, Gold, Crystal, Ruby, Emerald, Firered, Diamond, Platinum, HG, SS, and Black. Easily 1000+ total.
But If all my PS2 games (2000+) were added... Like 3000+.
All games together... I'd say 5000-6000. Maybe more.