Oxidum (Demo) is for version 1.3. It has 1 level and the file is 537MB in size. The file name is oxidumsh.zip. It was released on April 22, 1997. Note: The version I have has a bad METALICA.VOC file. I just deleted it before playing. According to the loading screen this is the shareware version of a full TC.

Oxidum has fair to good level design and gameplay. There is enough ammo but not a lot of health around. Be careful when entering a room or new area because what looks empty may not be. You need to activate a warp/time machine and travel to a ghost town in the year 1870, Place La Year (Los Angeles) in 2020, then back home.