What exactly happens when you get "Hidden movement"?

Game crashes immediately and puts me back to the desktop. I've noticed that sometimes it doesn't crash, maybe 1 time out of 10 I see the "Hidden movement" screen and then the next turn begins.
It might have to do with the fact that during "Hidden movement" you sometimes see a dark area where the alien moves, and sometimes you don't. I think the crashes occur in the latter scenario, but I'm not sure.

Thanks for your interest in helping me, it's greatly appreciated!

Have you tried DOSBox? I'm not sure if this is a protected-mode game or not.

Ok, I'll try that. So many progs...argh!

Thanks for helping me out, but DOSbox didn't work. It crashed with an error message about some function it didn't support. I used the latest 0.57 version... maybe X-com 2 is a protected-mode game, is there anyway to check?

If it uses DOS/4GW, it's protected mode.

0.57 isn't the ACTUAL latest release, it's just the latest public release. 😀

Here's a private release candidate for 0.58. Be careful with it.

This is strange...

The game uses DOS4GW, so DOSbox won't help. Yet I've made a discovery that seems to suggest that I've been on the wrong track all the time. To test if the game would crash I had a savegame with the same, early "terror" mission. Then I'd simply move some of the aquanauts out of the sub and end the turn. Most of the times this crashed the game, and if it didn't it crashed the next time I'd end a turn.

Now what I did was to run terrorcd.bat instead of terror.com or the VDMsound shortcut. When I tried the mission it didn't crash, and instead the mission failed saying "sub lost". This seems like a bug in X-com itself, but I can always start over. The game did crash spontaneously once during the mission, no clue why.

Another strange problem is the fact that the sound doesn't work (only music) when I run the bat-file, and if I use VDMsound the "old" crash problem is back. Oddly enough, disabling sound and/or music with terror.com does nothing. If I could get the sound fx working I'd be fully satisfied.

here's what the terrorcd.bat does:

@echo off
cls
%1sound\sndstart %1
%1ufoexe\black
ufoexe\geoscape "0" %1
if errorlevel 2 goto begin
goto end
:begin
%1ufoexe\black
ufo2exe\tactical "1" %1
:geo
%1ufoexe\black
ufoexe\geoscape "1" %1
if errorlevel 2 goto begin
:end
%1sound\sndend

It seems that I'm making progress here, but I'd still be grateful for any assistance.