That map was my favourite to play by a long way for ages and ages. For a month or two it was the only map I played in the game. I had the rank 1 score for it for a while, until the new breed of players arrived who use the bouncing strategy which I've never been bothered to properly learn.Good luck beating me on that one!
I'm happy they've taken steps to remove the bouncing tactic in DG2, though I don't blame people for doing it. It was easily the best strat if you can pull it off.
If you want a tip though.. Concentrate fire on the mid-right island from very early on, where you can have them enter and leave that island several times... then buff the upper mid island, routing them slowly round a longer and longer path with cheaper towers until most of the map is used. Eventually you will have a red kill zone on the mid-right, upper-mid, upper-central, and to some degree the entrance island, in that order of construction. I seem to remember having a bunch of meteors on the lower central island.
The main principle in DG1 (on the more open plan maps) is not primarily to make the longest path with cheap towers, but having a red kill zone that they walk through the most times possible.
Have you got DG2 yet Lightman? I have, but my Steam drive is on it's way out so I probably won't be playing it for a bit yet. You can get a headstart
I'm loving the graph thing on the top right for seeing how you're doing. That's going to make improving more fun.