Nitrus015: It's the original game files compiled into one place from what was originally two CDs, running with a patched executable and relying on Windows compatibility.

The quickandeasy EMI launcher and dgVoodoo shouldn't be necessary, though you may need dgVoodoo in case your specific machine can't run it with the Direct3D API it requires.

It's not using ResidualVM at all.

I have a Windows 10 x64, and In my case I didn't have any problems, I bought it, installed it, and ran it without a hitch.

So far, users on the forum have reported issues with a multi-monitor setup, some others needed dgVoodoo to run it with the Direct3D context, and others needed to install it on an NTFS drive since exFat (or perhaps FAT32) had given them issues with the CD check.

EDIT: And if you're interested in the actual engine name itself, it was called GrimE. LUA (I think 3.1) was used for scripting.

Nitrus015: You might want to take a look at this thread:
https://www.gog.com/forum/monkey_island_series/emi_launcher_17_for_escape_from_monkey_island

In short, dgVoodoo will let you play in any resolution you wish. (just remember to use the GOG executable, rather than a custom patched one).
I've been playing at 1920x1080 as far as Jambalaya so far, and have not ran into any issues.
Keep in mind that the game is still kinda 2.5D, so only the 3D geometry will truly benefit from an upscale. Backgrounds and other static images will remain the same.