Im a bit old school, but (roughly in order of age): Digger (mid 1980s PC) Super Mario Bros 1 (NES) Super Mario Bros 3 (NES) Ninja Gaiden 1 (NES) Double Dragon 2 (NES) Mega “Men” (NES) Sonic the Hedgehog (Genesis) Arkanoid (PC… various versions) Need For Speed 1 (PC) Need for Speed 2 (PC) Road Rash (PC) Deus Ex 1 (PC) These are the games I have re-played more than any others; more times than I can count.