Hello, yesterday i found out how to change the game's fps to any value you want, some common values you might want:
To apply these hex edits:

• Download HxD or any other hex editor
  
• Open BTD5.exe in the hex editor
  
• Do CTRL+R or find a replace button
  
• Replace the first value: 111111111111913F with the second

Notes:

V-sync should be on, so any FPS higher than your monitor supports should default to your monitor's max refresh rate.

Also there is a bug in the game engine where the game's FPS is slightly higher than the set value.
Stock 60 fps value becomes 64 fps, 240 fps becomes 250.

You can now create your own FPS values easily.

I made a python tool and have posted it to Github.

The .exe file:
https://github.com/Walter-o/BTD-fps-tool/releases/tag/1.0

The source code:
https://github.com/Walter-o/BTD-fps-tool

Now what is the story behind me finding out how this works?

I once asked in a forum how to mod BTD5's fps from 60 to 144 and i got this answer as response:
I thanked him and asked how he did it and he never responded.

Well a few days ago someone named Andrew added me and asked me if i knew how to mod the game to 240 fps.
And i didn't, i have tried reverse engineering the 144hz hex edit before but never managed to.

Yesterday i did another attempt and went to the location where the value was used in IDA disassembler, and i noticed tons of weird instructions happening, a lot of which that ended with `sd` and `ds`.

So i googled what those instructions mean and basically they are only used on "Double-precision floating point numbers".
And that was basically the answer, they are double-precision floating point numbers, they include an exponent and mantissa which goes way over my head for now but i at least know how to recreate the things in the Python programming language.

So the formula is basically this:

Take the fps you want, eg: then divide 1 by it: then create a hexadecimal representation of the exponent and mantissa of that floating point number: then reverse the endianness of that hex string:
And thats the entire process, i made python tool to automatically do this and it is now available in the "Create your own values" section.

To end this post i'd like to say ninjakiwi should add the option to change FPS ingame, it does not affect gameplay integrity whatsoever and would be a lot more user-friendly than opening a hex editor.

This post will be cross-posted across other BTD games that have the same engine and will be edited slightly if needed (most likely for BTD Battles since that one works a bit different)

Use any FPS [Bloons Monkey City]
Use any FPS [Bloons TD Battles]

Good luck everyone.