The 'Save Scumming' Feature Is Ambiguous... which toggle means you can't cheat?
OpenXCom has a setting to use a new random seed when reloading a save (or not). Unfortunately, the option and description are ambiguous and I don't know whether the YES or NO is meant to prevent cheating.
Solution 1:
The options are as follows:
YES - If you save, play a turn, then load and play that turn again, the results will be different. This allows you to repeatedly save and reload until your shot hits.
NO - The results of your actions based on random number generation will be the same even if you load a previous save and try again. This helps avoid the temptation to "save scum", as you know the shot will always miss. However, there are still benefits to saving and loading even with the same RNG seed.
XCom uses pseudo random number generation, meaning that the "random" numbers are actually predictable and predetermined. Even when using the same seed, if you miss a shot, but then load the save you made just before firing, you can know that your shot will miss and take a different action instead.
The only way to truly remove the benefits to saving and loading is to play in Ironman mode, preventing you from saving and loading (except on exit).
For more information about pseudo-random number generators, read RANDOM.ORG's excellent article which will explain it much better than I can. http://www.random.org/randomness/