Some things I think need some reworking:
I feel like the early game is way too rough since the constant amount of bloons in all lanes is too overwhelming what would help if bloon enemies in the early game weren't as scattered and that bloons would spawn focusing on certain lanes aka having 5 bloons spawn in 1 lane only would be easier to defend early.
Also, lead bloons are very tough with the only counter being cherry bomb maybe add potato mine for that also
It might be a lot of work but it would look way better if you didn't use any sprites from the original game and did all of the drawing.
Still think this is a cool idea for a small game