Left Alt and Right Alt are LEAP left and LEAP right. The MAME source explains the key combinations up top: https://github.com/mamedev/mame/blob/master/src/mame

Left Alt and Right Alt are LEAP left and LEAP right. The MAME source explains the key combinations up top: https://github.com/mamedev/mame/blob/master/src/mame/drivers/cat.cpp https://github.com/mamedev/mame/blob/master/src/mame/drivers... I tested them in Chrome on a MacBook Pro and they seem to work, but your mileage based on browser/OS/keyboard may vary.