I've got an 18 month old so completing games isn't something that happens too often. At the moment in my downtime from tinkering, I am playing:
MonsterWorld IV (Megadrive) - really good platform/RPG
Dragon's Lair (LaserDisc) - great for a quick play when I have five minutes.
Half-Life (PC Port) - never completed it back in the day so intent on doing that.
Killing Time (3DO) - FPS with some live action video and exploring mixed in.