You can play Wii games off-screen without the TV ever being on if you change your video output settings to be non-HDMI. Also, in non-HDMI mode, you can automatically start the Wii Menu on your GamePad screen by holding the B-button when you manually turn on the Wii U. 

I always knew you can play Wii games off-screen but I always thought I needed the TV on first because of the HDMI video setting! Did anyone else knew this was possible? 

Yeaa loll. I tried it a long time ago

Yeah i think thats not really useful though.
If you play wii games on the gamepad you still need to use the wii remote. :-/

It's helpful for IR sensing game when your TV room has horrible lighting. But for Smash Bros and VC games, it's pretty annoying :-/

Cool to have no TV connected to Wii U an option though.

It's pretty cool I guess, but I've never tried it myself.......yet!

I've played a pretty big chunk of Skyward Sword recently over the last few weeks using only my GamePad. Even though swinging the Wiimote at the GamePad looks like the most nerdy way of playing a video game ever in the history of everything, it actually works pretty decent.

I almost always play my Wii games on the Gamepad now, more convent for me. place the Gamepad has the wii sense bar built in so i don't need the TV for any functions. Kinda annoying that you do have to change the HDMI settings now which you didnt need to do untill a major updated happed a while back

Yeah, I once tried it. Could be pretty useful, I guess, but I just prefer playing it on a TV.

I would like to know why this isn't possible in HDMI mode? Why do you need to point at the screen first. Then it allows u to boot into Wii mode. Why doesn't the shortcut button just work all the time.

No idea. I figured out how to do this through a forum thread from google searching. Maybe it's because Wii has a 480P resolution or lower but HDMI's is higher  so it needs to check a connection first before playing off-screen? Who knows.