Ok so I didn't make the game and I'm not related nor did I help with Braian make the game but everyone will not stop asking how to play it or its not working so here is some help for you guys.
Step 1: Click the "Download" button that is red. (And wait about 1-2 minutes for it to download the Files/Folder)
step 2: Open your Files/Folder app (File Explorer).
Step 3: Find your "BTD But You're The Bloon" file.
Step 4: Click the file/folder.
Step 5: When you click the File/Folder another File/Folder will come up, press the one that comes up.
Step 6: When it comes with 5 things, press "Bloons But You're The Bloon" with the Unity logo on the left.
step 7: when a pop up comes up saying to extract the Files/Folder, press extract.
Step 8: Wait for it to extract
Step 9: Find the extracted file/folder and repeat steps 2-6
Step 10: Your done! You can now play the game. Enjoy!
More Information:
It doesn't work on iPad, iPhone, Android, Tablet, you get it.
It will only work on PC/Computer/Laptop. But most things that have a Keyboard will work, if your Device doesn't have a Keyboard it will most likely not work. Hope this also helps. And if you need more help DM me on Discord.