Very impressive.
I started up this game thinking what a new and odd idea an indestructible tank is, and I was pleasantly rewarded. Simply, this is an awesome and fun game. It's a little tough at times, but the free destruction at the end is rewarding. I wasted an hour playing this when I was supposed to be doing something, which stinks, seeing as I was supposed to do it.
Anyway, I have a few criticisms.
One, the enemies spawn irregularly. You've heard this before.
Two, I'm not totally sure if this is accurate, as I wasn't really paying attention when I saw it, but I could swear that when you run out of fuel, you blow up. LOL. Your own fuel is the only way to destroy the tank. (That could have been a glitch or something, or it could have been me not paying attention, but I'm pretty sure it was the game)
Overall, though, very good!