Originally posted by: Gibsons
Originally posted by: Mwilding
I think the key to bonus level 4 is getting the combo towers. 2000HP per shot and fire faster when upgraded. 5 of them would kill a bonus level 4 creep in 2 shots.
My strat:
Buy nothing but cannons for the first few levels. You only need one for the first level! At the first upgrade, get the fire tower upgrade and sell the cannons (except maybe one). One fire tower can get you through the first air level. Buy only fire towers and upgrades until level 28 or 31 (see below).
Remember a BIG part of the strat is to spend as little as possible. Ideally, you'll just barely clear each level. Pretty easy to judge what you need for most levels (sometimes you don't need to buy anything) until you get to a fast level, then you've got to beef things up. Air and immune levels are irrelevant since you've got all fire towers anyway.
Get the interest upgrades at 14 and 21. Get the water upgrade at 28, but only build one or none until you get to the first bonus level.
For the first bonus level, get 1-2 waters. You only need about 10 fire towers to get through the first bonus level. Quite a few more to get through the last one. The last level isn't hard per se, it's just hard to know how many fire towers you'll need (it's a lot though).
As for spacing, I don't think this game gives as big of a bonus for proximity as the other one. I've been concentrating my towers in the top middle portion. That way they (the fire towers) get three chances to shoot. This also minimizes the number of water towers needed in the "end game" to keep the creeps slow while the fire towers kill them. There might be better places to put them, but I don't know where.