I played and enjoyed this game many years ago. It is one of the wonderful franchises created by the EA murdered Origin (the game developers, not EA's client).
There are some mods to improve the graphics, such as SHTUP: http://www.moddb.com/mods/shtup-system-shock-2-texture-upgra…
More mods here: https://www.systemshock.org/index.php?board=2.0
I recommend anything by Vurt. he is responsible for several Flora enhancement mods for several Bethesda titles. I just install Flora Overhaul for Skyrim yesterday. http://www.nexusmods.com/skyrim/mods/141/
Other oldies on sale are the folllowing (I would prefer if they were this price on GOG though):
Darklands (an interesting DOS RPG set in the Holy Roman Empire) http://store.steampowered.com/app/327930/?snr=1_614_615_nigh…
Bad Mojo http://store.steampowered.com/app/255960/?snr=1_614_615_nigh…
Slave Zero http://store.steampowered.com/app/328470/?snr=1_614_615_nigh…
Eradicator http://store.steampowered.com/app/329640/?snr=1_614_615_nigh…
Shadowman http://store.steampowered.com/app/251770/?snr=1_614_615_nigh…
Classic Action pack (5 games including 2 deadlock titles) http://store.steampowered.com/sub/53355/?snr=1_5_9__403
Dragonsphere http://store.steampowered.com/app/327940/?snr=1_614_615_nigh…
Harvester http://store.steampowered.com/app/287020/?snr=1_614_615_nigh…
Colonization http://store.steampowered.com/app/327400/?snr=1_614_615_nigh…
Tex Murphy Complete http://store.steampowered.com/sub/45894/?snr=1_614_615_night…
None of the games are recommended for graphics whores though, though many indie games released today have pixellated, 8-bit type 1995 era graphics and people buy them and critics praise them. The first monitor I owned was only a 2bit, 4 colour CGA 320x240 display, so i have a certain tolerance for arachiac GFX.
A fantastic game at a fantastic price. It's also hard as nails, but that's half the fun.
Mods can make it easily look at least five years newer. When I played earlier this year, I found a great mod pack that included loads in one hit, but sadly the page it was on seems to have been taken down.
Here's the original link (in case it decides to work again):
http://neutralx2.com/2013/07/14/system-shock-2-mod-pack
But here's the list of mods in it if you want to download them individually:
SHTUP
Four Hundred
CyberBlutch Rebirth 3
SHMUP
Tacticool Weapon Replacements
Eldron Psi Amp
Vurt’s Organics
Vurt’s Flora Overhaul
Vurt’s Water
Vurt’s Hires Space
RocketMan Alternative Weapons Pack (minus the wrench. using tacticool pack wrench instead)
Proper Cigarettes
Cutscene Rebirth
Hi-Resolution Player Models
Earth New Sky
Olfred’s fixed objects
SS2 Simon Pennington HQ Droid – Edited by RocketMan/Grosnus