If you are looking for a free experience, consider these official alternatives:
: Prices range from $4.99 on Nintendo Switch to $14.99–$19.99 on Xbox and PlayStation 4 . Legitimate Ways to Play for Free
: Ninja Kiwi occasionally makes the game free for a limited time on the Google Play Store, though these promotions are rare.
: You can play a version of Bloons TD 5 for free online through authorized gaming sites like Kongregate . Note that this version may differ in content from the premium mobile/PC versions.