Owners of PlayStation consoles and Vita handhelds have long been accustomed to the luxury of cross-buy titles; you buy one version of the game and you get to play on your other devices gratis. That's a good deal and no mistake.
It's taken Nintendo a little while to embrace the concept for themselves – presumably because the underlying architecture of the Wii U and the 3DS are so different; it's not as simply as just hitting a button to port a game from one platform to the other.
Interestingly it seems the way cross-buy works on Nintendo systems is in reality far more generous that what you might initially have assumed. We received a tip from a reader that sounded too good to be true, so we tested it out for ourselves and it works an absolute treat.
Here's what you do:
1) Register several NNID accounts on your Wii U console.
2) Buy OlliOlli on the Wii U when logged into one of the NNIDs.
3) You can now download OlliOlli for free on any 3DS using one of the NNIDs which you registered on your Wii U.
We tested this with a Wii U which has three NNIDs registered on it and sure enough, we were able to obtain a free copy of OlliOlli on all three associated 3DS consoles. This behaviour is likely not supposed to be intentional, but if it is a loophole then it is a pretty cool one. This is only applicable if you're sharing a Wii U with others and you all have your own 3DS; ie families, house shares etc. Once NNIDs are tied to a system they can't simply be moved, so this isn't really open to 'abuse', as such.
This doesn't work with other "Cross-Buy" games such as Mario vs. Donkey Kong: Tipping Stars which was recently released in North America however as in this implementation you are just given a redeem code for your second copy, which you can of course pass on to a friend.
Our chums at Eurogamer received this statement from Curve Digital on the matter:
Before opting in to Nintendo's Buy One Get One Free initiative, the company made clear that we could do it one of two ways, and both were potentially open to exploitation beyond our control. Despite this, we're very happy with the cross-buy sales on Nintendo's platforms so far, and will be taking part in the initiative again where possible.
Thanks to retrohead for tipping us off.