I rarely buy apps, but I bought Threes. I would hope that anyone who's played and enjoyed 1024, 2048 or the myriad knock-offs would at least go and buy a copy of the app. It's a great little game and totally worth $2 (indeed, I'd say it's on par with the quality and playability of the early Nintendo "Game Watch" devices, and that's very high praise BTW. IIRC they retailed for around $25 in the 80's, so Threes is actually underpriced.)

Threes invented a wonderful game mechanic, and I'm reminded of the amazing indie games particularly on Kongregate. It's really something special to see all the creativity and joy that a great computer game can create.

My advice to the Threes inventors would be: rise above the imitators. Indeed, see them for what they are, gestures of respect (with the exception of 1024, who's makers are just assholes). One concrete step I'd take if I were you is to request that the web knock-offs in particular at the very least mention and/or link back to Threes (perhaps an iTunes link[1]).

[1] https://itunes.apple.com/us/app/threes!/id779157948?mt=8