Right now I'm trying to
finally finish Space Age.
I was playing Tomb of the Mask, but then I gave up after this last update because of some changes they did. I was up to level 14, so it wasn't going to be long to go before I got to the max 20 anyway. One of the nicer F2P games I've played in a long while.
Thinking of restarting Transistor because I'm stuck and I've probably now left it sitting for three months now because I don't have the right stuff to advance.
And I recently picked up the first Sonic again after it was announced it came out on Apple TV the other day. Was able to finally beat Marble Zone, but I keep dying during the Spring Yard boss because I keep falling through the holes left when the steps get taken out.

Maybe I should try with my controller instead, heh.
And yeah, Monument Valley was OK. There's a lot of stuff in the same category that I would rate higher than it.