Classic Defence Grid
There's only a couple of levels available at the moment, but it's Defence Grid through and through. Every good thing you could say about the original can be applied to what I've played so far. The thing that sets the DG series apart from other tower defence games is the ncredibly fun and fair level design. You have a failsafe button, much like other tower defence games but it never feels like you have to use it. With strategic tower placement you should, in a good tower defence game, be able to win fairly.
What I'm really excited to play around with is the malleable levels too. The one we're given access to here pulls it off incredibly well. You're given just enough space so that when the alien horde feels like it's about to overwhelm you an addition portion of the city rises out of the ocean just in time to save you. Great stuff.
I'm intentionally not going to mention and graphics or sound because whilst all of those things are fine for now at its core Defence Grid is all about the gameplay and as I said, what we've got so far is stellar stuff. Get your money down and if you already have Defence Grid 1 and the 2nd tier goal is met, do someone a huge kindness and gift it to them. I'm sure they'll thank you for introducing them to the pinnacle of the Tower Defence genre.