RGSS stands for Ruby Game Scripting System, a library that has been used in RPG Maker engines since RPG Maker XP. It's a Ruby library, and as such, all scripting is done in the Ruby language.
In all of its incarnations, RGSS has included objects and methods with which to handle graphics, audio, and data, including basic data structures for the RPG Maker engine. While it is designed specifically for RPG Maker, a talented scripter can create almost any kind of game with enough effort.
- The original version, RGSS, was released with RPG Maker XP and was based on Ruby 1.81.
- RGSS2 came together with RPG Maker VX and was, as RGSS, based on version 1.81 of Ruby; by default, its framerate was twice as high as RPG Maker XP's, and it featured more versatility.
- Ace is the third engine in a row that comes with its own scripting system, RGSS3, which, unlike the previous versions, is based on 1.92 Ruby, making it faster and more versatile.