I quite enjoyed Minecraft despite difficulty finding decent and persistent servers to play on.
I really enjoyed Super Adventure Box from the game Guild Wars 2.
This game here. It's like those two game modes combined. Granted it is one of those 'free to play cash shop game' scourge. Yet you get a lot out of it for being a free player, which is a big plus. But how is it that it flew under the radar for me? Was it not really advertised well at launch?