The AC-HELP.EXE that comes with the freeware release says you need at least 517k of free conventional memory to play the game (561k to play with SoundBlaster music and effects), so you should have enough memory to play the game.

Try starting the game with 'carnage info'. It should show you the game version as well as the current settings (SoundBlaster configuration etc.).

It's possible that your copy of Alien Carnage got corrupted at some point (disk errors or a virus) so you might also want to check your system just in case. Also make sure that all the HARRY*.-0 files are present in the game directory. Those are all renamed executable files, each responsible for different aspects of the game. If one of them is missing, then the game won't work correctly. You can still get the original freeware release of Alien Carnage from the old 3D Realms website without having to create a user account or anything like that. Copy those files onto your system (perhaps into a different folder) and see if that version works correctly on your system.

I want to say that this game needs FILES=30 in CONFIG.SYS , I have had this issue with some game that I am almost sure it was Halloween Harry ... give it a shot if you don't have the FILES line , could be complete bs though and I remember wrong!

Tried several versions of the game and settings for config.sys - unfortunately both didn't work.

Tried several versions from different sources and all known parameters (/c, info, slowpal, nopage) but nothing happend - the game simply won't respond 🙁
Here the result with HH1.exe, but all other versions are no different:

Booting without mouse and CD support didn't change anything either 🙁
And the sound parameters are also OK.

Maybe it's something else hidden in the config.sys or autoexec.bat?

CONFIG.SYS

1DEVICE=C:\DOS\HIMEM.SYS /testmem:off
2DEVICE=C:\DOS\EMM386.EXE RAM D=32
3BUFFERS=15,0
4FILES=40
5DOS=UMB
6LASTDRIVE=F
7FCBS=4,0
8DOS=HIGH
9DEVICEHIGH /L:1,26928 =C:\SB16\DRV\CTSB16.SYS /UNIT=0 /BLASTER=A:220 I:5 D:1 H:5
10DEVICE=C:\SB16\DRV\CTMMSYS.SYS
11COUNTRY=049,850,C:\DOS\COUNTRY.SYS
12DEVICE=C:\TOOLS\CDPRO\VIDE-CDD.SYS /D:MSCD001
13STACKS=9,256

AUTOEXEC.BAT

1@ECHO OFF
2PROMPT $p$g
3PATH C:\WINDOWS;C:\DOS;C:\TOOLS\NC;C:\TOOLS\TP;C:\TOOLS\TP\UTILS
4SET TEMP=C:\TEMP
5SET SOUND=C:\SB16
6SET BLASTER=A220 I7 D1 H5 P330 T6
7SET MIDI=SYNTH:1 MAP:E
8C:\SB16\DIAGNOSE /S
9C:\SB16\SB16SET /P /Q
10LH /L:0 C:\DOS\SMARTDRV.EXE /X
11LH /L:2,912 KEYB2 GR,,C:\DOS\KEYB2.SYS
12LH /L:1,32096 MSCDEX /D:MSCD001 /m:8
13LH /L:0;2,3104 /S C:\TOOLS\CTM\CTM-DE.EXE

I would suspect corruption of the game, but you say you tried several versions...

Try running it in safe mode (press F5 when DOS starts booting to skip config files).

Finally got it - and yes, it seems that (all) the exe files were corrupted.

In any previous attempt I first unpacked the ZIP files on my Win 10 machine and then burned an ISO/UDF CD from this files*.
Never had any problems with this approach until, but somehow in this special case this must have rendered the files unusable.
Now I've just burned the ZIP file and uncopressed in under DOS and voilà, that did the trick 😀
... but still don't understand why.

Many thanks to all & best wishes for 2020

***case closed***

* JFYI: the file attributes ("read only" and "archive") were always removed after copying the files from CD.

glad you found the issue!!!
well it might worth to install a NIC on your retropc and use mTCP's FTPserver to transfer files from modern-pc -> retro-pc
certainly faster and less hassle than burning cds

Yes, this CD burnig business is a bit annoying but on the other hand the 486 is my only machine I have to do this.
All others (with Windows 95 or later) are network-ready or have USB 😀