Yeah the contour looks like the SEI case. SEI was in Cali, a bunch of doctor investors iirc got together but didn't make it past this one release, pressure from NOA.
Problem is, IM2 was handed down from AVE, which in turn I think was ported from Epyx on the PC. So any "proto" would just really be like their own test cart, not any real developement that would have an early ROM or anything. But still great internal company history.
-------------------------