Defense Grid 2 isn't doing anything I haven't seen in previous tower defense games, but it does it all so well. It doles out little rewards at a devious pace, keeping me glued to my desk. There's always something new to see or play with: the next tower, upgrade, seeing how the wave next wave unfolds or what the new planet looks like.
One of the biggest problems with any tower defense game is that you often don't know you've set up your towers the wrong way until it's too late, and since progress is made at the enemy's pace, it can take a long time to implement what you've learned. Defense Grid 2 lets me go one wave back each time I press backspace. It takes a second. It turns failures into opportunities to experiment with new strategies rather than opportunities to stop playing.
After 14 hours with DG2, I still find better ways to snake the alien's path or prepare in the first waves. With multiple difficulty levels, an easy-to-use cooperative mode, and a level editor, 14 hours could easily turn into 100. It's a great tower defense game and nothing more, but it hooked me in a way that more ambitious games rarely do. 076b4e4f54