Touching up the die revealed an ID:
Sea of gates, uncommitted logic array, or whatever the cool kids use these days. See for example: http://stardot.org.uk/forums/viewtopic.php?t=8539
These will need layout extracted to emulate. While this is doable (ex: http://visual6502.org), its a lot of work with current polygon capture tools. Additionally, emulating the logic may require a different workflow than used by ROM emulators.