Ninja Kiwi's popular tower defense game, Bloons TD 5, has dropped to free for the first time on the Google Play Store. The game has an incredible amount of levels and upgrades, which offers a lot of replayability.
Bloons TD 5 has cartoonish graphics, and features an army of monkeys, which are your towers, battling against the evil Bloons, aka balloons. There are no pre-defined spots for placing towers, so you can place the tower wherever you want to. There are around 21 towers with abilities (powers), and each tower can be upgraded in one of two paths. Don't worry, enemies, aka the Bloons, also have special units, to counter your towers to offer a great challenge. The game offers co-op multiplayer for 2 players as well.
Bloons TD 5 normally costs around Rs. 200, but you can get it free from the Google Play Store for a limited time (for 7 days only). You can see the days left for the sale from the Play store app.
I have played the Humble Bundle version of Bloons TD 5, which is devoid of In-App Purchases, but the Google Play version has some IAPS, but they are optional. Though the developers do update the Humble Bundle version, it is much easier to keep the Google Play version updated.