Chronotron
You had me at "time-travelling robots."
Chronotron: Lemmings with paradoxes. It's a cute, smart puzzle game in which you overcome obstacles with the help of your past selves. Kind of like Back to the Future 2. Kind of.
It hinges more on timing and memorisation than Prince of Persian time-rewinding (though that is an option in the event of minor error) - if a door can only be unlocked by standing on a nearby switch, you need to go stand on that switch for a few seconds. Then trundle back to your TARDIS, hit space, and a clone of yourself will spawn. He'll duly repeat your exact actions up to that point - so while he's stood on the switch, you nip through the door. Simple, right?
Not for long. Skip forward a few levels and you're managing maybe four versions of yourself. Not only are you working out the timings necessary to unlock your path through the level, and ensuring each of those clones is set up to do exactly the right thing at exactly the right time, but you need to be careful not to cause a paradox - for instance, accidentally locking in one of your innocent time-clones so he can't return to the TARDIS. If he can't return, then you could never be where you are now and... ow.
I kept finding myself annoyed because one of the other robots was doing something wrong - leaving a switch too soon, or foolishly getting himself stranded in a pit, and every time I had to remind myself "no, he's me. Even though he's right there on the screen, behaving apparently autonomously, he's an exact mirror of my earlier actions. Anything he does wrong is my fault entirely." And then I would flagellate myself 200 times, until I knew better.
Chronotron quickly becomes fairly challenging, but in such a way that you'll feel remarkably smug for 10 ten minutes after besting a troublesome level. Alternatively, you'll take one look at the next level, attempt to picture quite how many time-displaced robots you'll need to navigate all its doors, bridges, switches and elevators, and feel remarkably tired all of a sudden.
Certainly I feel worn out after wrapping my head around a few levels, but also satisfied and pleased - you really should go play this.
With Braid also promising time-travelling brainy platforming in the (hopefully) not too distant, it's shaping up to be quite the year for indie chrononauts.