At an evening in December 1996, celebrating the 50th anniversary of the Bennekomse Schaak Vereniging (the chess club of Bennekom, a village in the Netherlands; I was a member of this chess club for many years), several chess variants were played. One of these variants (and one traditional chess players were bewildered of most) was Rifle Chess.
Rifle Chess, also called Shoot chess, or Shooting chess, was, according to Pritchard's Encyclopedia of Chess Variants, invented in 1921 by W. B. Seabrook, who was inspired by modern warfare tactics, where, unless in ancient warfare, where a close combat was necessary to kill an enemy, now the striker can kill at a distance. The game has been played since then at many occasions.
The rules of orthodox chess are followed, with the following exceptions.
Pieces no longer take by moving to the square that is occupied by the piece they want to take. Instead, when taking, the piece that takes does not change location. Effectively, this means that when one could take a piece under the traditional chess rules, one can remove the opponents piece but no of ones pieces is moved. One can always take at most one piece per turn.
Pritchard states, that one often uses the rule that taking is obligatory, although when more choices are available for taking, one can choose which capture to make.
This simple rule change changes the game a lot. For instance, it is of no use to guard pieces.