what did you expect? the game is written in java

Just saying that it's not really running in the web browser, merely displayed within it. And won't run today.

To "run in the web browser" you mean rewriting the game in javascript.

No, webassembly wasn't a thing yet at the time (arguably still isn't). I'm not sure emscripten existed, and even when it works it turns 20KB C++ binaries into 3MB of broken javascript. Non-starter for a performance-sensitive game engine.