The Hidden Below

Demo version

The demo version of the game has death graphics for bad guys. However in the full version, they simply disappear when defeated.

Because of this, the demo version readme states that while the demo can be freely distributed, it can't be given to minors, which is presumably why the death graphics were removed from the full version (so it could be more widely distributed).

Innovations

The Hidden Below is reputed to be the first German made FPS game and the first PC first-person shooter in which you can look up and down, beating Raven Software's much more widely known DOOM engine based game Heretic, which boasted a similar feature, by a few months. The Hidden Below came out in August, Heretic in December.