Several Google Sites and GitHub repositories host unblocked versions of the game to bypass standard web filters:
In the mid-2000s and early 2010s, a specific sound defined the computer lab: the rhythmic, repetitive thwip-thwip-thwip of digital darts firing at a steady pace. This was the sound of Bloons Tower Defense 5 (BTD5). For a generation of students, BTD5 was not merely a game; it was a rite of passage, a lesson in resource management, and the premier method of covertly avoiding schoolwork. The phenomenon of "unblocked games"—specifically the quest to play BTD5 on restricted school networks—represents a unique intersection of strategy gaming, digital rebellion, and the enduring appeal of the tower defense genre. bloons tower defense 5 unblocked games
You can play directly in a browser without needing administrative rights to install software. Several Google Sites and GitHub repositories host unblocked