"Survivor" Deep Space
Survival mode eschews the leveling-up modus operandi for a time trial. The longer you keep the explosiveness going, the better your score. If you want to want to use your weapons, though, you'll need to level it up a few times in the "Classic" mode to have much of a chance, so make sure to spend some time there first. The rest of the bells and whistles are the same as in "Classic", so it's really just a different approach to let you show off all the skills you learned in the first mode.
Another nice facet of the game - and all Live Arcade titles, for that matter - is that there are a whole slew of achievements to build up your Gamerscore. For those of us that like to see that number go up on a regular basis (I know my hand is raised) it's yet another reason to really spend some time digging into and spending quality time with the various parts of the game.
The only true deficiency to Astropop is that there's no multiplayer, which just doesn't seem quite right. I can definitely envision racing against a buddy to level up faster and/or get higher scores while playing side by side - or even in a virtual picture-in-picture. There are leaderboards, of course, but it's clearly not the same. About the only thing to be hoped for here is a future expansion to allow blowing up thousands of colorful blocks in a more social atmosphere.
Astropop is certainly not going to change the gaming world, but we don't think that was what it was built to accomplish. What it does do - like several of the titles in the ever-expanding and surprisingly successful Xbox Live Arcade - is provide a lot of fun in a challenging way at a more than reasonable price.