Likewise. I had one game where I had a 256 block and two 128 blocks, but I ran out of room to maneuver before I could combine the 128s to another 256 and then combine the 256s to a 512.

by pressing up-right-down-left, then repeat, I managed to get to 512 two times...

I did it by pressing up-left-down-right, repeating each direction as many times as possible. That's the worst part - knowing that your carefully calculated playthrough is actually no better than someone just pressing the keys in a set order.

Ran your strategy 162 times with autoit of which the following blocks came by: [128]: 150 times, [256]: 36 times, [512]: 13 times, [1024]: 0 times. Anyone else a good suggestion for an optimal "blind" strategy?

Perhaps I had a little bit of luck. But this shows you can easily get to 256 with little dedication. After which you can start to puzzle things together.

Also about your autoit "analysis" 36 + 150 + 13 != 162

Well, when it reaches a 256 block, it also reached a 128 block, so some games count for 2 or 3 blocks.

That's true. :)

Anyway managed to get to 1024 + 512 + 256 after that without random button mashing.

UUDDLRLRBA

I prefer Trip actually, it has the same rules as Threes, but it's much harder to get a high score compared to Fives. Because you only ever get 1, 2 or 3 as the new card, everything needs to be built up from there, it requires a lot more thought and planning. https://play.google.com/store/apps/details?id=ca.ginik.trip

You might also want to check out Even -- http://bit.ly/even-game -- have fun!