The alter, change, or build upon PC game code to add features, content, and/or, desired improvements is, of course, known as modding. Thanks to the largely unpaid efforts of these "amateur" programmers, many a game has been given new life, courtesy of the fan-created content that pops up. While those who limit their gaming to the console environment miss out video game modding, the PC gaming community embraces it quite vigorously. So much so that Steam features a Workshop area for games that allow modding that feature the necessary files to alter your game experience.
One game that has an incredibly active community is Bethesda's Skyrim. To put it mildly, there are mods for just about everything in open-world RPG. If you want to add a realism mod that requires your character to relieve their bladder, among other things, you can do that. If you want to add lightsabers to the vast armory that's already available to players, you can do that too. Do you want your games to have a more, um, adult theme, complete with character nudity? Skyrim Nexus has just what you need; although, apparently the site is undergoing some DoS trouble.
There is a new mod, however, that is making news because it brings the powers of Dishonored, another Bethesda title, to the world of Skyrim. If you haven't had a chance to play Dishonored, needless to say the main character's powers are certainly a highlight, especially the "Blink" function. The idea of making this particular skill set to available to Skyrim characters at least looks like a brilliant idea:
If you're interested in learning another skill to vanquish your enemies throughout Tamriel, Skyrim Nexus again has the goods. Just be patient with the site as it deals with DoS griefers.