Not that you can trust user reviews on iTunes, but one player of Anomaly: Korea recently praised the reverse-tower-defence game as being "one of a kind". That's false.
Anomaly Korea is actually very, very much like 2011's Anomaly: Warzone Earth</em>, the reverse tower-defence game. You still command a slow-rolling column of tanks and transports through a maze of evil enemy towers. You can still map out your route through the city streets using your fingers. You can still tap special power-ups into existence to briefly buff your vehicles or baffle your foes. You can still kill towers, collect money and upgrade your vehicles. You still need to get to a goal point with some vehicles. The game still checkpoints, makes you think, plan and re-plan, getting tough nice and quickly.
Really, not much has changed. We're in Korea this time, not Baghdad, which is simply licence for the game to switch to an oddly un-specific oh-that-sounds-kind-of-Asian soundtrack and switch some of the stilted voice-acting to Korean-accented-stilted-voice-acting.
So, no, there's not much new here. A new tank type, a new power-enhancing buff, a new gimmick with airstrikes, a new super-tough series of "Art of War" challenges that restrict you to using a level's minimally possible array of power-ups. If your memory of the first Anomaly is slightly fuzzy, you probably won't even notice what's new.
The good news is that Anomaly Korea might as well be two of a kind. The game is fantastic. It played well last time. It plays well this time. Each level has its own gimmick — a race against time, an ability to call in bombing runs, etc. There's no great new idea or tweak in the game, but it barely matters. On iPad and iPhone 5, tethered with cloud saves, I found that the game still plays really well.
Is it a sequel? Is it more of a mod? Who cares. It's three bucks right now and extremely good. Get it.