Another tip: For the Treasure Hunting, you can get better odds by starting in one of the corner squares. The numbers can count diagonally, so 3 can be 3 diagonal, or 2 diagonal and 1 straight. The only worry is that you only have 3 clicks, so corner, far diagonal point, then deduce from there, but it's not 100% accurate this way, as you can have 1-3 overlapping squares that fit this bill.
Protips: you can collect loot with your cursor. The 4 boss tentacles can't be disabled with pirates. The amount of damage you need to soak for the kraken is way too high from the first time you get to it. Normal Cannons are the most useful, beyond pirates for swarms of ships and the ram for travel.
The asteroid isn't worth very much, is it? This game had a few jump bugs where going maximum depth to jump out of water didn't actually launch you some of the time. Otherwise, it's good for what it is.
On the right side "Want a reward follow us" green button, you can just open the links and close them before they load, you'll get 12 stars and 6k for it. You don't actually have to follow 'em.
The paratrooper pigs are horrible design. Had a helicopter hit one on a bounce and it was still alive. No upgrade should ever feel punishing like that. The Rump Roast upgrade makes up for it, but waaay into the upgrade tree, which doesn't actually make up for it until you're already done with the game and have to redo everything anyway.
You can also abuse the pause/unpause to make a unit fire and shave about a second or two off it's next shot fired. This can help in earlier waves for amped up levels.
You can get negative values of fire rate. This however doesn't do anything due to each tower having an animation frame-rate. (Ergo it needs to play through the whole animation every time.) You can pause/unpause to make the animation play through during the paused phase and it'll fire on the next unpaused phase though.
I'm on a slightly laggy connection, so it's loading and "need to resync to server" every 2 minutes. A game like this shouldn't have that sort of loading load on it, but design-wise I'd say it's a good version of this type of game.
Max Coin caps are kinda funky and arbitrary. Could definitely use a rework on how it's calculated. Something like Baseline (1-5) + 0.2 (total coin value in level) + current number... or something like that, so that getting a 50 value coin doesn't amount to getting 3 coins because of a cap.
Correction: Coins when erased will return to your counter if you save and test play. Lava doesn't hurt. Enemies could use a bit of tweaking to be more manageable. Owl-type ones for example are being aggressive before they're even on-screen, when they appear to need "startled" to be aggressive.
 "Pirateers"){kind=icon}
 "New York Shark"){kind=icon}
 "5 Differences"){kind=icon}
 "Kamikaze Pigs"){kind=icon}
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 "Hands of War Tower Defense"){kind=icon}
 "300 miles to Pigsland"){kind=icon}
 "Wooden Path"){kind=icon}
 "Bunny Invasion: Easter Special"){kind=icon}
 "Papa's Burgeria"){kind=icon}
 "Sandbox Hero"){kind=icon}
 "Swords & Potions 2"){kind=icon}
 "Deeper Sleep"){kind=icon}