EPIC sets standard VGA video modes and then checks to see if the mode sets were successful; however, when setting mode 13h it includes the high bit to skip clearing video memory and expects the BIOS to echo that bit back when the current video mode is queried. So, just as it used to be with DOSBox, you're probably looking at a compatibility issue with a particular video card's BIOS. I suppose it's possible that the BIOS does different things based on the type of connection between the card and the monitor, but the game itself is ignorant of the connection.

If the issue is what I think it is, you can work around it by making a small modification to the game executable. In START.EXE at offset 13A31 change 93 to 13.

Thanks. It worked.

It seems that while things appear to be the same on the surface for both VGA and DVI, some underlying stuffs were different, and this was one example.

The problem affects all video cards that are being connected to the monitor with a non-VGA connection (like DVI and HDMI) regardless of video card. Setting mode 13h with high bit set (93h) seems to be something exclusive for VGA, and doesn't work with others, but seems like few games actually used it while EPIC did.

Setting the high bit in the video mode number should simply tell the BIOS to skip the step of clearing (writing zeros into) video memory as part of the mode set, and the connection type seems rather irrelevant to that. Perhaps it's true that some video BIOSes treat the high bit of the mode number differently on digital connections for some reason, but if so then it apparently causes a loss of some legacy compatibility as a result.

It seems that EPIC doesn't really have a purpose in skipping the clearing of video memory when setting mode 13h, so the workaround should have no ill effects.