I'm using Opera and it started getting too slow to play. When I investigated the opera.exe process it was using over 630MB of RAM. Took a long time to close the browser.
Using Chrome this page managed to choke my entire system including task manager, so I couldn't get a look at the process but it had chewed through 2GB - OS for sure because the hard drive was continually accessed.
I found it interesting that javascript with canvas works on the iphone. (Albeit slow on my 3G only ~5fps - and since it uses keyboard control, you can't get out of the cage.)
Once I got to the second screen, crouching and shooting one of the guards prevented me from getting back up. I could still shoot, but none of the other buttons were responsive and I got stuck in a crouched position.
I'm not sure what you mean by "back in the day". I played it the first time a year or so ago, and was consistently impressed at the design. The gameplay holds up very well against today's best.
Using Chrome 4.0.223.16, it's peaking at 125, but typically holding around 99. On the death screen it dipped to 66 a couple times, which is strange since there isn't much going on there.
It had a remarkably good story considering the lack of dialog, narration or any other story telling elements. A real work of genius that truly stands the test of time.
Reading the original game author's page about the creation of Another World, I was surprised to see he worked on the graphic design for Future Wars, a game I remember enjoying immensely at the time.