And so today I finally got to the Portal 2 themed levels of Defense Grid. The first of which was nothing special - the second of which was excellent. Not only did you have GladOS taking the piss out of you the whole way through, but you also had the invaders trying a few tricks that they hadn't used before. Having to juggle myself against two different ways of attacking at the same time really kept me on my toes.
If you haven't played Defense Grid before then I recommend you download the demo, and if you have, then go take a look at the new levels, they're awesome fun.
Original post on Dreamwidth - there are comments there.