thoughts on Desktop Tower Defense

Played a ton of Desktop Tower Defense yesterday.  If you haven’t seen it, “creeps” enter the field from the top and left of your screen, and try to leave via the bottom and right.  You place little towers to take them out, and stopping them earns you gold, which you can use to lay down more towers or upgrade the ones you have.
I survived all 49 levels earlier this morning, and I’ll share a little of what I know before I retire completely.  I’m not going to walk through each type of enemy, tower, and boss, but there are a couple of things I figured out that might help you.

First-level thinking (and you get past this if you read the “quick start”) is: let’s block their path!  If we make them take a long, circuitous path, then we have more time to sap their health.  There are lots of schools of thought on how to make the most effective labyrinth, but my first instinct was to build a quick, corner-to-corner wall, and make the enemy traverse the length and width of the field two or three times.  You can also create more dense, edge-to-edge walls, but the important thing is that you control their flow.
If you look at the boards of the top scorers, you’ll see that many of them never upgrade their pellet towers.  These cheapest towers in the game don’t really upgrade well, and I’ve had luck leaving them as level 1.  Not everything on the board has to be working for you if you are doing a good job of blocking.  As a matter of fact, you might see that some of the top boards have only six or seven fully upgraded towers, and a bunch of pellet towers.  Since the number of enemies is finite, so is your income, and as much as we’d like to have 20 maxed out squirt towers, there isn’t that much money in the game.  It’s surprising how well one frost tower and four squirt towers can cope.  On the other hand, I’ve seen a few boards with maxed-out pellet towers, but don’t get confused: a level 1 tower of any type is really just a wall once you hit the mid-game.  99% of your damage is going to be done by upgraded towers.
Different configurations have different strengths and weaknesses.  You might find that the second or third flying wave completely overpowers you, or maybe the immune waves go through too fast.  That might mean you’re relying too much on darts or frost towers.  The game definitely encourages balance, once you figure out the basic strategy.

Most of the top scorer boards don’t have a lot of air defense.  Anti-air towers only fire on flying targets, and they don’t do an amazing job of that.  They aren’t a great investment.  Squirters do a lot of air defense if you have them near the middle, and frost towers also work.  The flying boss is nearly impossible without some seriously upgraded anti-air, but if that boss goes through untouched, how much does it hurt you?  2 health.  That’s all.
Most top scorers have a single point of entry into a maze.  That means blocking the entry ways, so when 10 come from the left and 10 come from the top, they end up having to enter a narrow passageway at about the same time.  If you’re not using frost and darts, this doesn’t matter - the other tower types don’t have “splash”, or do damage to nearby enemies as they hit their target.  But a long stream of enemies can quickly become a bunched-up, slowed down, heavily damaged clot when you get them to show up in a long corridor together.

Once you figure that out, you realize that you’re not really building walls to keep your enemy from leaving, but to route them back to your main, upgraded weapons.  With the right layout, an enemy might have to walk in the range of a maxed-out dart tower five or six times before it finally gets a clear look at the exit.

This might be obvious, but upgrading takes time: specifically, downtime.  You have to upgrade sometime, but there are ways to optimize.  Dart towers are useless during flying waves, and frost towers are pointless during immune waves.  Beyond that, I try to upgrade one piece at a time.  Since you only have a handful of really useful towers, you don’t want half of them down for an upgrade at the same time.  Besides, having money for two upgrades at the same time means you didn’t upgrade when you could have done the first one, so you screwed up once already.  That money doesn’t earn interest.

I only rarely sent a wave in early.  I am pretty sure that you have to survive the game to have those bonus points count, and I don’t see the advantage.  There are levels that seem to end “early”, and you might jump ahead there, but it doesn’t happen a lot.  (Again, your enemies are your source of income, so jumping ahead is not really a serious disadvantage if your maze can take it, and if you can build out that fast.)

Another thing you might notice is that the top scores are littered with half-filled boards, and a smiley face or a signature at the bottom.  I imagine that these players have sold off their towers as they beat the last guy.  Selling towers is important at the beginning of the game: you get a pretty good price for your used towers, and you definitely don’t want to leave gaps where you’re planning future development.  Stick in a 5-gold pellet tower, reclaim your 3 gold when it’s time to sell, and don’t lament the 2 gold you lost.

Another strategy I never implemented: juggling.  If you’ve ever opened up a hole by accident while upgrading, you know that the enemy is always recalculating the optimal (shortest, not “least damage”) path to leave.  If you have him running down three long hallways and something changes in the maze so he’ll only have to run down two, he’ll backtrack to go through the hole you just made.  (If you haven’t played, note that it’s illegal to put down a tower that would actually prevent the enemy from leaving.)  It wouldn’t be hard to create a couple of key points in your maze where the sale of a tower here and the erection of another one somewhere else would result in a particularly nasty enemy backtracking as many times as you had gold to do it.  I imagine the game essentially comes down to this on “hard” and “challenging”.

Anyway, the strategy of this game is amazingly deep, and the “live action” aspect of it means that even the best strategies can be unsuccessfully implemented.  The masterstroke of the developers was to show off the boards of the best players: you can gain a ton of useful strategy information from reading these boards and seeing how people play it.  If you haven’t played, give it a shot and let me know how you like it.