Nymes: Hm... that leaves mostly platformers and the like, I think. I can strongly recommend
Hotline Miami, if you haven't played it yet. Although it may take more than ten hours to complete. Or maybe
Odallus - The Dark Call or
VVVVVV, which I both have yet to play ;-)
Nice suggestions, but I've already played (and completed)
Hotline Miami and
VVVVVV and I down't own
Odallus - The Dark Call.
So here's a list to choose from:
Second Sight (might take a little longer than 10 hours)
Tiny and Big: Grandpa's Leftovers
Mutant Mudds
Unmechanical Extended (just the new content)
Snapshot
Incredipede
Retro City Rampage
Lucius
99 Levels to Hell
Zafehouse Diaries (I'm not sure how long it is)
Driftmoon
Reus
Amnesia: The Dark Descent
The Adventures of Shuggy
The Lords of Midnight
World Rally Fever (not sure how long, but I assume one can play it in between more complex games)
Race the Sun
Surgeon Simulator 2013
Outlast
Giana Sisters: Rise of the Owlerlord
Sang-Froid: Tales of Werewolves
Shelter
Long Live the Queen
Octodad: Dadliest Catch
The Swapper
Tales from Space: Mutant Blob Attacks
Teslagrad
American McGee's Grimm (probably longer, but it seems to be a number of short episodes)
InFlux
Stick it to the Man!
Mark of the Ninja
Schein
Fractured Soul
Clarc
Mousecraft
Reprisal Universe
Anomaly: Warzone Earth
World of Goo
Metrocide (no idea about the length)
The Fall
Rebuild 3: Gangs of Deadville
Gurumin: A Monstrous Adventure
Apotheon
Anodyne
The Last Tinker
Lula: The Sexy Empire (I had the retail version and I think it was quite short for a management game)
Never Alone
Card City Nights
Another World: 20th Anniversary Edition
80 Days
Pony Island
Deadbolt
Duskers (probably longer, but it seems like a good game to play a mission once in a while)
Bit.Trip Beat
The Westport Independant