Ghost Hacker 2
If you haven't played the original Ghost Hacker, then you're probably not going to have much of a clue of what's going on in Core Sector's Ghost Hacker 2, but if you're a tower defense fan, then it's very much worth your while to find out. Place towers and power them up with nodes to defend your cache of data cores from incoming hostiles in each level. Or, if playing in Monster Mode, swarm a devious layout of towers and traps yourself by deploying enough minions to capture all the cores yourself. Feeling puny? Then replay stages on harder difficulties to earn more cores to permanently upgrade your structures and abilities, or try a level again with an entirely different layout of towers and powers.
Considering the original Ghost Hacker came out almost three years ago, it's sort of surprising that its sequel doesn't offer any sort of synopsis to bring you up to date on who everyone is and what's going on. Even if you've played the first game, three years is a long time, and I can't even remember what I had for breakfast today. While not significantly different from the original, however, Ghost Hackers 2 engages with its strategic gameplay, replayability, and sleek cyberriffic visual style. Just stand on your chair and loudly proclaim "I FIGHT FOR THE USERS" and then sit back down and play some more.