Don't let the "super" beginning of the boss rush fool you - It's easier to do the entire boss rush than it is to kill the final boss of the normal game, as the one you fight in the boss rush is significantly nerfed. If you can complete the game on normal, you can clear the boss rush in a few tries.
This game is basically identical to the first one. The only difficulty is early (This includes most of the challenges as well) and the game is easily broken by going Max Regen/Defense. Max cost/extra plants next, followed by attack, and that will carry you through everything else.
The inability to target units closest to the exit is bad enough, but when you add units that can dodge it makes it even worse. I'd only recommend this for serious fans of the genre.
Easy badge takes less than 10 minutes to complete. Get two from stage 1 (They're in nearly the same spot, turn left and go down at the end for the second one), then run stages 2 and 3 to get 1 from each.
Same problem as the last time this was BotD. Get to the 5th map, and all the plankton is blue, but none of the polyps are, making the game impossible to complete.
I've had no problems with controlling the character at all and the BOTD took.. Like 35 minutes. I'll probably be done with the entire game within an hour.
From what I saw up until I completed two rounds, it felt pretty random how many monsters spawned per map, meaning it pretty much goes down to luck. I went from $1,700 short in game one to $600 over in game 2 despite the fact that I took damage during game 2. Wave 6 in particular had an absurd amount of mobs the second game. I've also found first map could give anywhere from $1,200 to $2,000.
Same problem at the anchor. Blue plankton only and it wants everything but blue, so I can't make any progression and got stuck at the same spot. They combined an slow, boring game, with the chance of being broken and impossible to finish. Real winner of a BotD here.
If you want the easy badge quick, just do only bombers and miners and you should be done within 5 minutes. Getting 75 is easy with everything but homers maxed, and maxing the homers will get you both the third badge and the height badge. It doesn't take 15 minutes to get all 4 badges if you do it in the right order.
Skip the first two challenges, as they're two of the worst in the entire game. Most of the challenges after the first two stages are pretty easy. Max regen, then defense, and the game pretty much crumbles away from there anyway. I'd suggest maxing attack and crit after that to speed things up. Don't even bother with spells early on - You won't have a lot of mana to play around with most of the game and the spells cost too much at early levels.
I remember playing this a couple of years ago and wishing I had stopped playing it much sooner than I did, and seeing the comments here jogged back some memories. Snag the easy badge and move on. There's nothing worth playing here.
My random death sequence on "normal" difficulty: 2 swordsmen/1 militia, followed by 3 swordsmen/1 archer, followed by... 8 swordsmen/2 archers/3 knights/4 militia. It's entirely random how long the game decides to let you live. Even with every peasant in a militia it was a slaughter