To recap, the basic premise of both games is that this is a tower defense game unlike any other. You start off with a single command station in space, and the only way to build more towers is by adding structures to the open sides, expanding outwards and creating a network of defense. As you protect each planet, you have to make sure that you build enough solar panels. These act as your power source, and your defenses will shut down without them. This game has a much larger variety of weapons and defensive tiles to choose from, but the asteroids have also grown more diverse and dangerous. The campaign is now well defined, with the many planets and moons of our solar system acting as different levels. Each level is usually capped with a massive asteroid that looks big enough to have killed the dinosaurs, which is basically a boss battle. Upon completing the campaign, survival mode is unlocked.
The art has been massively upgraded from the first. Guns are now easier to tell apart, and everything has a uniform look to it. All the effects are shinier than ever too. Gameplay is mostly the same, but with more variety and balance changes. It feels like the game has been tweaked a lot since the last one. There is a handy help section detailing every structure, asteroid, and power up should you ever need reminding. This is a five dollar app, and I feel the game is worth the asking price. If anything, you can download the original game first entirely for free as a kind of demo. Just keep in mind that the sequel has a much higher level of variety and polish. Download the free Appolicious Android app