Two tweaks for Internet Arcade games on archive.org

The Internet Arcade has a great collection of browser-playable arcade games. But I ran into two problems: (1) the aspect ratio goes bad in full-screen mode (no black bars on the sides of 4:3 content), and (b) mouse support is turned off, which makes trackball games like Marble Madness less fun and spinner games like Blasteroids not great for those of us who have a USB spinner (I just made one myself using a magnetic rotary sensor). 

It took me a while to find a solution, but finally I managed to inject options into the underlying MAME emulator and thereby fix both problems:

First, go to a game, but don't click the start button.

Then put the following into the URL bar and press enter: 

javascript:MAMELoader.extraArgs=(z)=>({extra_mame_args:['-mouse','-keepaspect']});AJS.emulate()

(Note that Chrome will not let you past the "javascript:" prefix into the URL bar. You can copy and paste the rest, but you have to type "javascript:" manually.) The game will start, and the mouse will be enabled. You can add other MAME options if you like.

You can also turn this into a bookmarklet. Indeed, you can just drag this to your bookmark bar: Emularity Mouse .

There is still a minor aspect ratio problem. If you go to fullscreen and go back to windowed view, the aspect ratio will be bad in windowed mode.