If you only want the classic Flash demo:
The developer, Edmund McMillen, remade the entire game as The Binding of Isaac: Rebirth using a modern engine (C++/HTML5 export). This version: The Binding Of Isaac Unblocked No Flash
Several websites and developers have created versions of The Binding of Isaac that can be played in a browser without Flash. These versions often use HTML5, JavaScript, or other technologies to replicate the game's mechanics and graphics. Players looking for "The Binding of Isaac Unblocked No Flash" can find these versions through a simple web search. However, it's essential to be cautious and use reputable sites to avoid malware or other security risks. If you only want the classic Flash demo:
When you search for "unblocked" games, you are usually trying to bypass: Because The Binding of Isaac is graphically violent
Because The Binding of Isaac is graphically violent (featuring themes of bodily harm, religious horror, and disturbing imagery), it is often aggressively blacklisted by default by these filters.