Some games don't support it. Only certain ones do, but both the games you mentioned should play off the GamePad as they are supported.
http://mynintendonews.com/2013/01/03/these-are-the-announced-wii-u-games-that-use-off-tv-play-feature/
Assassin’s Creed III
Batman: Arkham City Armored Edition
Ben 10 Omniverse
Call of Duty: Black Ops II
Darksiders 2
FIFA 13
Just Dance 4
Little Inferno
Madden 13
Marvel Avengers: Battle for Earth
Mass Effect 3
Mighty Switch Force: Hyper Drive Edition
Nano Assault Neo
NBA 2K13
Need For Speed: Most Wanted
New Super Mario Bros. U
Ninja Gaiden 3: Razor’s Edge
Nintendo Land
Puddle
Rabbids Land
Scribblenauts Unlimited
Skylanders Giants
Sonic & All-Stars Racing Transformed
Tekken Tag Tournament 2: Wii U Edition
Trine 2: Director’s Cut
Warriors Orochi 3 Hyper
Toki Tori 2
Tank! Tank! Tank!
The Screamapillar is easily identified by its constant screaming—it even screams in its sleep. The Screamapillar is the favorite food of everything, is sexually attracted to fire, and needs constant reassurance or it will die.
