What we have here is a great example on improving an existing formula, they already had the skeleton of a game, and then built upon it to make something pretty cool. The new additions from the first game, such as another 2 tracks, a new tower, 2 types of single use placeable objects, and a few new bloon types make for a game that's far more varied right off the bat.
These are all implemented rather well as well, with the placeable road spikes and glue making the game a bit more lenient in regards to making mistakes without completely trivialising the game, due to how cost inefficient they are. This allows the player to be able to recover from mistakes without giving them the opportunity to rely on them too much. The boomerang tower is also quite a nice addition, acting as non-explosive group damage in order to have a way of better dealing with explosion resistant bloons, immediately giving way to more strategic diversity, along with giving a 2nd tower that is able to shoot frozen bloons. This indirectly makes the ice tower more usable, effectively bringing up the amount of new towers by 2, since it was completely useless in the first game.
It's really the new bloon types that make this a considerably better game however, with the rainbow bloon acting as a stronger DPS check than just spamming lower level enemies, and the lead bloon acting as a major reason to prioritise getting explosives early on. Giving the player such early goals shows a much better understanding of effective game design that the first game lacked, and a similar thing is done with the very early, powerful rainbow bloon round ensuring that players have spread out their defences rather than concentrating everything in one location. All of these lead to making a game that while still quite limited in certain respects, goes far beyond its predecessor and makes for a somewhat entertaining diversion that even has a bit of replayability thanks to it having 3 tracks. This is where I can see why people having some fondness for the series, as it definitely shows a lot of promise and for a flash game is just all in all very competently put together.
These are all implemented rather well as well, with the placeable road spikes and glue making the game a bit more lenient in regards to making mistakes without completely trivialising the game, due to how cost inefficient they are. This allows the player to be able to recover from mistakes without giving them the opportunity to rely on them too much. The boomerang tower is also quite a nice addition, acting as non-explosive group damage in order to have a way of better dealing with explosion resistant bloons, immediately giving way to more strategic diversity, along with giving a 2nd tower that is able to shoot frozen bloons. This indirectly makes the ice tower more usable, effectively bringing up the amount of new towers by 2, since it was completely useless in the first game.
It's really the new bloon types that make this a considerably better game however, with the rainbow bloon acting as a stronger DPS check than just spamming lower level enemies, and the lead bloon acting as a major reason to prioritise getting explosives early on. Giving the player such early goals shows a much better understanding of effective game design that the first game lacked, and a similar thing is done with the very early, powerful rainbow bloon round ensuring that players have spread out their defences rather than concentrating everything in one location. All of these lead to making a game that while still quite limited in certain respects, goes far beyond its predecessor and makes for a somewhat entertaining diversion that even has a bit of replayability thanks to it having 3 tracks. This is where I can see why people having some fondness for the series, as it definitely shows a lot of promise and for a flash game is just all in all very competently put together.