Let's start with the obvious:
Monkey Island in the hands of Ron Gilbert.
Now the rest.
The Secret World - greatest writing of *any* MMO out there (yes, including FFXIV) and most single player games. Bad marketing, deep complexity and some design choices didn't make it popular enough. Shame, the complex lore and the investigative quests alone make it a masterpiece in my eyes.
Final Fantasy - It's dead. Need to go back to its roots. And they need to kick out nomura for it to happen. fuck nomura.
The Elder Scrolls - same as FF.
Chrono Trigger - need an explanation on this? Really?
Ultima - The legend needs to return. Also needs to look at its roots to recapture the magic.
No One Lives Forever - Greatest single player shooter ever, imho. Fantastic cast and humour, smart, great maps, great gunplay.
Oni - Greatest Bungie game, easily.
Blood - didn't care much for 1, but I loved 2. Maybe it should stay dead, though... PC culture would ruin it.
Shogo: Mobile Armor Division - I fucking loved it. "On foot" levels were mediocre, but once you got on the robots it was so fucking fun. This really needs an updated version.