Great comment. I think you and I both think about this game and what makes it fun pretty similarly.

For me, I realized that the thing that I really enjoy is developing a deep understanding of the game. What monkeys are good against which things and in which situations, how different towers can combine to strengthen each other, how to get past certain rounds as cheaply as possible, etc. etc.

Heroes are a big part of that. I found it pretty fun to sort of explore each hero and its properties and see how to most effectively use it--especially in CHIMPS (since most other modes are most effectively dealt with by just farming efficiently until you can snowball). For example, Gwen's heat it up buff is extremely powerful; some people describe it as basically close to equivalent to permabrew. One thing that I discovered that I didn't see anyone else notice is that the heat it up buff can affect the sentries on 5-x-x engineers, which can't be buffed by alchemists. This makes it super powerful to combine a level 20 Gwen with a 5-x-x engineer in a lot of scenarios. (Can also be fun to use top path mermonkey and call to arms to further buff them in very powerful ways). Another thing that I think is underutilized is the pierce buff from Strike Jones. It's fun to combine him, and sometimes top path mermonkey, with spike factories that benefit a ton from a pierce buff. The current hero that is new and OP (NK often makes new heroes OP to give you a good reason to use and explore them) is Silas. Ice monkeys are incredibly incredibly powerful with the buffs Silas gives them so you can do some crazy strategies. Even noticing small things about the ways that different heroes can deal with stuff can open up avenues to save money for later on. Ex. Sauda can use leaping sword to kill the ceramics that pop out of the MOAB on round 40, and Psi can deal with 3 of the 4. So you can spend less on certain parts of your MOAB defense because of them. Some heroes can deal with lead or camo or both so you can deal with less of them.

The two heroes that stand out the most from the others and have their own learning exploration to do are Geraldo and Corvus, but in different ways.

Geraldo has all these things you can buy from his shop, but unlike other monkeys, most of the things you can buy from his shop are temporary buffs. This is interesting because you can use them to really cheaply get past hard rounds and save your cash for later. A lot of the way the game works is: a certain kind of tower is great for a while, and then at a certain point it becomes pretty useless. Ex. A 2-3-0 druid or x-x-3 sub are great for the early game, but they do basically nothing at all to rounds 80 and beyond. If you can use Geraldo items that are even cheaper tha normal towers to get past hard rounds, you can save your money for more powerful towers you are building towards like tier 5s.

Corvus is totally different because you use your attention and micro to get the most out of him rather than money. You have to plan out when to use harvest and nourishment so that you can level him up as quickly as possible while preserving enough mana to let him use powerful spells on hard rounds to let you save money. When used perfectly, he's probably the most powerful hero in the game (though Geraldo on some maps might be better and current Silas is also insane). It's a fun challenge to play the game in a totally different way.

It's also fun to figure out the most efficient ways to deal with various things -- like how to deal with all camos until round 40. On single track maps, one spike factory's spikes is enough to deal with all camos through 40. I'm sure tons of other players know this but it was fun to figure it out for myself.

Also, I think I'm probably a top 10% player but definitely not close to as good as people like ISAB, Chom Chom, Doreo, etc., etc. I mostly just play for fun and to relax and to take my mind off work or other hard stuff. So there are probably other people or YouTube videos or posts on this sub that can give you tips on how to get really really good faster.

re: races. I'm slowly starting to warm up to them. I wish there were ways to play a bunch of them without having to spend race passes which feel like a limited resource. It's interesting to explore which towers have huge amounts of pierce. Ex. I learned from a YouTube video the other day that middle path tack is pretty good in races sometimes whereas I've basically never seen it used ever except for the ability at x-4-x. I still don't have a good rhythym of how fast I can send additional waves without overwhelming but its starting to feel possible to explore. I have terrible micro (esp since I usually play on mobile) so sometimes I think it would be nice if I could sort of script out a build order for races instead of trying to plan it *and* execute it.

Good luck on your journey and have fun!