Heh, it looks like this will be the year the TD's finally find their way into the 4k (I've seen a sneak peak of another one).
This one plays pretty good! I found the start to be very (too) hard, but it's way too easy later on. I do have a few suggestions, and some other thoughts:
- Graphics! With this much room to spare, surely you can add some nice procedural graphics. First, I suggest you enable antialiasing (everybody like antialiasing). For the tower range indicator, you might add another, filled oval with a transparent color. Transparency is always nice. For the towers, you might do fillRoundRect instead of fillRect... and so on.
- Right click to deselect current tower would be nice.
- More distinct towers. Perhaps different attack speeds? Also, bullets should be marked depending on tower type (different geometrical shapes, size, colors (darker version of the tower's color?) - something like that).
- I couldn't really tell whether green towers were stronger against green enemies? A more clear relation between enemy colors and tower colors might help. As an alternative, add another tower that's pretty much the only thing that can damage a certain type of enemy... so you'll have to get a few of those towers.
- Slow towers or splash towers are pretty much standard in TDs. Consider adding one (or both) of those.
- It seems to me that the only viable tactics is getting *a lot* of green towers. And then perhaps getting the expensive ones later on (levels 50+ or so). Some rebalancing is needed.
- Clicking the timer to advance to the next level is not at all intuitive to me. Perhaps a button that says "Spawn", "Next wave", or something such?
- A "restart" button (or key) would be nice, for when you know you're doomed. Perhaps restart by pressing R or something.
- With this much room to spare, there's no need to skip the window title. Add a title and it'll get easier to find in the task bar

- Each time I click the mouse to place a tower (whether I actually can afford it or not), the game freezes for a few frames. This causes the game to sometimes place the tower in the wrong place (if you move the mouse while it's frozen). If I click a lot, using a tower I can't afford, I can effectively "pause" the game (but not the timer, since it's clock based). I'm not sure whether there's any actual value in doing this, but if you added, say, a "splash attack" tower, it would be abusable (as you can make enemies spawn on top of each other).
Oops... that post got pretty long. Much like sws26 said, it's too easy later on. I lost 17 lives early, and then not a single one until level 180... and I didn't build anything after level 30 or so. I had 3074 gold and 3639 points when I died at level 186. And since I wasn't really using my money, I know you can get way beyond the level I got to.

EDIT: One of the reasons the post got so ridiculously long was because JGO went down as I was writing it... so I had a lot of time to add to it while it was open in notepad
