If you're an Android user like me, then you might be a lot more familiar with the Threes! copycat, 2048. Both games took their respective app stores by storm as a simple numbers game with a simpler swipe mechanic, but now you can play the original in your browser.
I was waiting for a long time for this to be made available on the Google Play store, but long before that happened, 2048 had soared to popularity. The Android game eventually became more famous, so much so that Threes! actually got in trouble for mentioning its copycat on its store page. It's an example of how ludicrous situations can get with app cloning.
Threes! is a littler harder than 2048, as you're dealing with multiples of 3 instead of 2. After playing it on the web though, you'll probably want it on your phone, too.