Vector TD 2
The overall goal of any tower defense game is to prevent the enemy from reaching the end of the maze. You do this by placing units alongside the path that will fire (or perform other helpful actions) when an enemy is in range. With each foe you destroy you earn cash, allowing you to purchase new towers or upgrade existing ones on-the-fly. Everything is handled with a simple mouse interface and is remarkably intuitive, even for tower defense newbies. You can even specify which Vectoids certain towers target, forcing them to focus on weak, tough or the nearest enemy.
Analysis: Combining retro-style visuals with the tried-and-true tower defense formula, Vector TD 2 preserves everything we loved about the original and multiplies it, adding new maps, more units, and additional game modes such as time attack, lightning, and a curious puzzle/sandbox mode ($50,000 budget, you don't earn cash, see how long you can survive). The basic game is the same, but the strategies you'll use to win will be quite different.
What makes Vector TD 2 especially unique are the bonus points you can spend to buy special support towers. These units can either be placed on the battlefield, such as the damage booster that increases the power of nearby units, or used immediately like the interest increase bonus. Do you go for the kill or stock up for more towers? It's your call.
More of the same great (and great-looking) tower defense strategy from one of the best games in the genre.