I've been attempting to catalog all of the EGM editorial supplement booklets up until around March 1995, when they switched to single page fighting game move inserts (and immediately after, mini strategy guides). I felt that these supplements, especially the CES previews, were actually extensions of the issues they were bundled with, so to me it feels like the scans are missing content without them.
These are editorial supplements, I did not attempt to include supplements that were pure advertising or otherwise provided by external sources. I also did not include posters. These are the supplements that are magazine-sized, say "editorial supplement" on the cover, and were produced by EGM staff.
There are 18 total if you count the Cinescape preview issue, I've uploaded uncorrected 600dpi JPGs here, in folders marked with which issues they go with. If anyone would like to edit these and put them on Retromags, feel free:
https://www.dropbox.com/scl/fo/5qgaxjc89sms465ek7f9a/AHoHueRMYILZviFr7-4XnGw?rlkey=kk3plt15m17kn1ch0w071t1dm&dl=0
I determined this through a combination of sealed issues that we own, live auctions on eBay, and archived auctions on WorthPoint. At this point I am confident that this is all of them. The only one I cannot substantiate its mate for is "EGM's Video Game Accessory Guide," it's somewhere around issue 40 but I have not found any evidence of where it belongs.
I also included a stack of subscriber-only pages, though I have not tracked whether this is the complete set, nor did I attempt to figure out which issues they go with...a project for another day, maybe?
There are also seven editorial inserts for EGM2, and several for Electronic Games and Computer Game Review, which maybe we can collectively track, but they're much rarer than EGM's...