I found that upgrading nothing until the missile towers works well enough. Also, once the nuke trucks start coming, it's a good idea to buy the extra wall strength then. They can be easily taken out with a well-placed shotgun shot, but some insurance is nice.
Thanks for everyone's guides, they're really helpful!
Actually, disregard the laggy comment as I didn't read before that it was there to make the game more of a challenge, which makes the game even better in my eyes.
The drawing seems a lot buggier than before; I find myself having a lot of gaps due to lag at times. Not too crazy about the new crumpled paper background; I liked the plain white just fine, as well as the variety of colors from 2. All in all a good addition to the series, though, especially in the variety of obstacles. Still a 5/5.
Wow, third time playing the game and I get a really lucky Day 2 to get into space on Day 3 with only the initial launch.
Actually have a badge for that kind of luck would be ridiculous though.
 "Bloons Tower Defense"){kind=icon}
 "Line Game"){kind=icon}
 "SeppuKuties"){kind=icon}
 "Storm the House 3"){kind=icon}
 "colourPod"){kind=icon}
 "Draw-Play 3"){kind=icon}
 "Hedgehog Launch"){kind=icon}